Do the souls which attained moksha in this creation again come back to earth to undergo birth and death process in the next creation which takes place after mahapralay?
Normally liberated souls don't come back in any cycles but if they want they can. So, there is a choice.
Wherever he stays, he enjoys supreme bliss. The proficient in Yoga should practise these five Dharanas.
Then his body becomes strong and he does not know death. That great-minded man does not die even during the deluge of Brahma.
104-105. Then he should practise Dharana for a period of six Ghatikas (2 hours, 24 minutes). Restraining the breath in (the region of) Akasa and contemplating on the deity who grants his wishes – this is said to be Saguna Dhyana capable of giving (the Siddhis) Anima, etc. One who is engaged in Nirguna Dhyana attains the stage of Samadhi.
Within twelve days at least, he attains the stage of Samadhi. Restraining his breath, the wise one becomes an emancipated person.
Samadhi is that state in which the Jivatman (lower self) and the Paramatman (higher Self) are differenceless (or of equal state). If he desires to lay aside his body, he can do so.
108-109(a). He will become absorbed in Parabrahman and does not require Utkranti (going out or up). But if he does not so desire and if his body is dear to him, he lives in all the worlds possessing the Siddhis of Anima, etc. 109(b)-110. Sometimes he becomes a Deva and lives honoured in Svarga; or he becomes a man or an Yaksha through his will. He can also take the form of a lion, tiger, elephant, or horse through his own will.
Ordinarily a person after attaining knowledge of Brahman is not reborn.
But, the case of those who have a divine mission to fulfil is different. Those perfected sages have one or more births until their mission is fulfilled.
यावदधिकारमवस्थितिराधिकारिकाणाम् ॥ ३२ ॥
yāvadadhikāramavasthitirādhikārikāṇām || 32 ||
- Of those who have a mission to fulfil (there is corporeal) existence, so long as the mission is not fulfilled.
Here is the Shankara Bhashya on this verse:
Rishi Apantaratama was born again as Vyasa. Sanatkumara was born as Skanda. So also other Rishis like Vasishtha and Narada were born again. Now these Rishis had attained the knowledge of Brahman, and yet they had to be reborn. If that is so, what is the utility of such knowledge of Brahman?—says the opponent. This Sutra refutes it and says that ordinarily a person after attaining Knowledge is not reborn. But the case of those who have a divine mission to fulfil is different. Those perfected sages have one or more births until their mission is fulfilled, after which they are not born again. But then they never come under the sway of ignorance although they may be reborn. Their case is analogous to that of a Jivanmukta, who even after attaining Knowledge continues his corporeal existence as long as the Prarabdha Karma lasts. The divine mission of these people is comparable to the Prarabdha Karma.