The detail story of Rishi Vishwamitra creating another new creation and a second Svargaloka (Heaven) is also can be found in
Book 7 - Chapter 14 - of Devi Bhagavata Purana. Chapter Name -"On the going to Heavens of Triśaṅku and the commencement of Hariścandra’s narrative".
Background - Once during famine king Satyavrata ,on seeing poor condition of Rishi Vishwamitras family supplied them the food ,when
the rishi was engaged in Tapasya and was outside of his ashrama. One
day the king didn't got any food (meat) and he slaughtered the
Kāma Dhenu (the cow giving all desires) of Vaśiṣṭha. Knowing this
Rishi Vashistha became angry and on account of the killing of his cow,
called the King by the name of Triśaṅku and made him a Cāṇḍāla.
Hearing about his help Vishwamitra was pleased with Trishankand decided to
free the King of his curse, The king also asked Vishwamitra about a
way withwhich he can go to the Heavens in his present body.
Vishwamitra then gave the King all the Puṇyams (merits) that he
collected for himself. Thus by virtue of the Muni’s Tapas "Trishanku
went up in the heaven.
When Trishanku reached heaven ,the gods seeing him thus spoke to Indra.
9-20 Thus getting up and up, when the King reached the abode of Indra,
the Devas, seeing the terrible Cāṇḍāla-like appearance of Triśaṅku,
spoke out to Indra :-- “Who is this person coming like a Deva with a
violent speed in the air? Why does he look like a Cāṇḍāla.
Indra disliking Trishankus presence in Swarga loka again dropped him on earth.
Indra said - You are a Cāṇḍāla, quite unfit for the Devaloka; so where
are you going? You ought not to remain here; so go immediately back to
the earth. O Destroyer of the enemies! Indra speaking thus, the King
dropped from the Heavens and, like a Deva whose merits had been
exhausted, fell down immediately.
While coming back to earth from heaven Triśaṅku cried and said to Vishwamitra.
“O Viśvāmitra! O Viśvāmitra! Being displaced from the Heavens I am now
falling very violently; so save me from this trouble.”
Upon hearing his cry and seeing him getting down, Viśvāmitra by virtue of the Tapas kept stationed him in midway. And started creating new creation.
O King! Hearing his cry and seeing him getting down, Viśvāmitra said
:-- “Wait, wait.” Though displaced from Heaven, the King by virtue of
the Muni’s Tapas, remained stationed at that place in the middle of
the air. Viśvāmitra then began to do Ācaman (sip water) and
commenced his great Sacrifice to create another new creation and a
second Svargaloka (Heaven).
Seeing his resolve Indra became very anxious and came down to Vishwamitra and said to Vishwamitra."There is no necessity to create another new creation".But Vishwamitra was determined one. And asked Indra to take Trishanku in his own abode.
Indra accepted that
22-31 Vyāsa said :-- O King! Indra was thoroughly aware of his
determined resolve and very powerful asceticism; so he accepted to do
according to his word, out of terror. The Lord Indra then gave the
King a bright and divine body and made him take his seat in an
excellent car and taking leave of Kauśika went with the King to his
So there is not much info. here in this purana about What happens to his creation.But it's clear that Vishwamitra through his merit (Tapas) created different creation i.e. Grahas ,Nakshatras ,lokas etc. including Swarga loka (Heaven).
The description of Sage Vishvamitra creating another creation is also there in Skanda Purana Book VI - Nagar Kanda - Chapters 2-7.
Here we can see the every detail of his creation in Chapter seven.
॥ सूत उवाच ॥ ॥ एवं ध्यायमानेन जलमाविश्य काम्यया ॥
संध्याद्वयं तच्च दृश्यतेऽद्यापि वै द्विजाः ॥ 1 ॥
1 Suta said - witha keen desire , he entered water and began to
meditate. Then he created two sandhya's (twilights). O Brahmmanas they
are to be seen even today.
ततो देवगणाः सर्वे सृष्टास्तेन
वैमानिकाश्च ये केचिन्नक्षत्राणि ग्रहास्तथा ॥ 2॥
मनुष्योरगरक्षांसि वीरुधो वृक्षसंयुताः ॥
सप्तर्षयो ध्रुवाद्याश्च ये
चान्ये गगनेचराः ॥ 3॥
एवं हि भगवान्सृष्ट्वा विश्वामित्रः स
2-3 Thereafter all the groups of devas were created by
that nobel-souled one. Persons travelling in aerial chariots ,stars
and planets , human beings ,serpants and Rakshasas ,creepers and
trees; the seven sages (Great Bear) ,dhruva and others (pole star
etc.).And sky walkers were created.
स्वकीयेष्वथ कृत्येषु योजयामास तांस्ततः ॥ 4 ॥
एतस्मिन्नेव काले तु
द्वौ सूर्यो युगपद्दिवि ॥
उदितौ रात्रिनाथौ च जाताश्च द्विगुणा
द्विगुणानि च भान्येव सह सप्तर्षिभिर्द्विजाः ॥ 5॥
4-5 After creating these , the angry sage Visvamitra employed them in
his own work At that time two suns and two moons rose up in the sky
simultaneously. There were two set of planets.Two sets of stars along
with the great bear came up , O Brahmanas.
एवं वियति ते सर्वे स्पर्द्धमानाः परस्परम् ॥ दृश्यंते द्विगुणीभूता
जनविभ्रमकारकाः ॥ 6॥
6 Thus they competed with one another and were seen doubled causing
chaos and confusion in the minds of the people
Then Lord Brahma assured Vishwamitra that your creation will stay as it is , but they will never be eligible to share YAJNA and other rites.
भविष्यति ध्रुवा विप्र सृष्टिर्या भवता कृता ॥
परं सर्वेषु कृत्येषु
यज्ञार्हा न भविष्यति ॥ 18 ॥
18 O Brahmana , what has been already created by you shall certainly
come to stay. But they will never be eligible to share yajna and