"Charaiveti" is a famous Vedic Mantra. It means keep moving on (if I am not wrong). From which verse this word is taken? What does the entire verse say?
This is from Rigveda's Aitareya Brahmana 7.15 :
अथ हैक्ष्वाकं वरुणो जग्राह तस्य होदरं जज्ञे तदु ह रोहितः शुश्राव सोऽरण्याद्ग्राममेयाय तमिन्द्रः पुरुषरूपेण पर्येत्योवाच नाना श्रान्ताय श्रीरस्तीति रोहित शुश्रुम पापो नृषद्वरो जन इन्द्र इच्चरतः सखा चरैवेति चरैवेति वै मा ब्राह्मणोऽवोचदिति ह द्वितीयं संवत्सरमरण्ये चचार सोऽरण्याद्ग्राममेयाय तमिन्द्रः पुरुषरूपेण पर्येत्योवाच पुष्पिण्यौ चरतो जङ्घे भूष्णुरात्मा फलग्रहिः शेरेऽस्य सर्वे पाप्मानः श्रमेण प्रपथे हताश् चरैवेति चरैवेति वै मा ब्राह्मणोऽवोचदिति ह तृतीयं संवत्सरमरण्ये चचार सोऽरण्याद्ग्राममेयाय तमिन्द्रः पुरुषरूपेण पर्येत्योवाच आस्ते भग आसीनस्योर्ध्वस्तिष्ठति तिष्ठतः शेते निपद्यमानस्य चराति चरतो भगश् चरैवेति चरैवेति वै मा ब्राह्म-णोऽवोचदिति ह चतुर्थं संवत्सरमरण्ये चचार सोऽरण्याद्ग्रामनेयाय तमिन्द्रः पुरुषरूपेण पर्येत्योवाच कलिः शयानो भवति संजिहानस्तु द्वापरः उत्तिष्ठंस्त्रेता भवति कृतं सम्पद्यते चरंश् चरैवेति चरैवेति वै मा ब्राह्मणोऽवोचदिति ह पञ्चमं संवत्सरमरण्ये चचार सोऽरण्याद्ग्राममेयाय तमिन्द्रः पुरुषरूपेण पर्येत्योवाच चरन्वै मधु विन्दति चरन्स्वादुमुदुम्बरम्सूर्यस्य पश्य श्रेमाणं यो न तन्द्र यते चरंश् चरैवेति चरैवेति वै मा ब्राह्मणोऽवोचदिति ह षष्ठं संवत्सरमरण्ये चचार सोऽजीगर्तं सौयवसिमृषिमशनायापरीतमरण्य उपेयाय तस्य ह त्रयः पुत्रा आसुः शुनःपुछः शुनःशेपः शुनोलाङ्गूल इति तं होवाच ऋषेऽहं ते शतं ददा-म्यहमेषामेकेनात्मानं निष्क्रीणा इति स ज्येष्ठम्पुत्रं निगृह्णान उवाच न न्विममिति नो एवेममिति कनिष्ठम्माता तौ ह मध्यमे सम्पादयां चक्रतुः शुनःशेपे तस्य ह शतं दत्त्वा स तमादाय सोऽरण्याद्ग्राममेयाय स पितरमेत्योवाच तत हन्ता-हमनेनात्मानं निष्क्रीणा इति स वरुणं राजानमुपससारानेन त्वा यजा इति तथेति भूयन्वै ब्राह्मणः क्षत्रियादिति वरुण उवाच तस्मा एतं राजसूयं यज्ञक्रतुं प्रोवाच तमेतमभिषेचनीये पुरुषं पशुमालेभे॥7.15॥ ~ 7.15
This part of Aitareya Brahmana is describing the story of Harishchandra, Rohita and Shunahshepa. In this section Rohita was searching a ransom and Indra kept on motivating him by saying चरैवेति (keep moving / wander).
Varuna now seized Harislchandra, and his belly swelled (i. e., he was attacked by dropsy). When Rohita heard of it, he left the forest, and went to a village, where Indra in human disguise met him, and said to him, '' There is no happiness for him who does not travel, Rohita ! thus we have heard. Living  in the society of men, the best man (often) becomes a sinner (by seduction, which is best avoided by wandering in places void of human dwellings) ; for Indra surely is the friend of the traveller. Therefore, wander ! "
Rohita thinking, a Briihrnan' told me to wander, wandered for a second year in the forest. When he was entering a village, after having left the forest, Indra met him inhuman disguise, and said to him, " The feet of the wanderer are like the flower, his soul is growing and reaping the fruit ; and all his sins are destroyed by his fatigues in wandering. Therefore, wander ! "
Rohita thinking,, a Brahman told me to wander, wandered then a third year in the forest. When he was entering a village, after having left the forest, Indra met him in human disguise, and said to him, " The fortune of him who is sitting, sits ; it rises when he rises ; it sleeps when he sleeps ; it moves when he moves. Therefore, wander !
Rohita thinking, a Brahman told me to wander," wandered then a fourth year in the forest. When he was entering a village, after having left the forest, Indra said to him, " The Kali is lying on the ground, the Dvapara is hovering there ; the Treta is getting up, but the Krita happens to walk (hitber and thither).' Therefore, wander,.wander ! "
Rohita thinldng, a Brahman told me to wander, wandered for a fifth year in the forest. When he was  entering a village, after having left the forest, Indra said to him, " The wanderer finds honey and the sweet Udumbara fruit ; behold the beauty of the sun, who is not wearied by his wanderings. Therefore, wander, wander ! "
Rohita then wandered for a sixth year in the forest. He met (this time) the Risi Ajigarta, the son of Suyavasa, who was starving, in the forest. He had three sons, Sanahpuchha, Sunahsepa, and Sunolangula. He told him, " Risi ! I give thee a hundred cows ; for I will ransom myself (from being sacrificed) with one of these (thy sons)." Ajigarta then excepted the oldest, saying, " Do not take him," and the mother excepted the youngest, saying, " Do not take him." Thus they agreed upon the middle one, Sunahsepa. He then gave for him a hundred cows, left the forest, entered the village, and brought him before his father, saying, " my dear (father) ! by this boy I will ransom myself (from being sacrificed)." He then approached Varuna, the king (and said), " I will sacrifice him to thee ! " He said, " Well, let it be done : for a Brahman is worth more than a Ksattriya ! " Varuna then explained to the king the rites of the Rajasuya sacrifice, at which, on the day appointed for the inauguration (abhishechaniya), he replaced the (sacrificial animal) by a man.