Kripalu Ji Maharaj says that ‘Anybody who is a ‘Mukt Jeevatma’ will also go into the ‘Paramatma phase’ only for a short duration and ‘Has to return to this world’. Because when ‘Jeevatma is reunited with Paramatma where is the question of His return? Can you please elaborate on this?
The first type of jeevan mukt is one who has fully purified his mind through sadhana, thus he has no remaining desires or attachments. These desires and attachments are called avidya maya. They can be conquered through one's own sadhana, because they were created by the mind and have no existence outside of the mind. This jeevan mukt is said to be liberated from avidya maya, and may spend long periods of time absorbed in samadhi. However, the mind of this jeevan mukt is still mayic - it is in a pure, sattvic state of maya, but still contains the unlimited past sanskars from unlimited past lifetimes. Those sanskars cause him to come out of his samadhi, and as soon as he does, he is liable to be attracted by the world again and start desiring and developing attachments. That is why Ved Vyas says 'jeevan muktaa api punarbandhanam kaam karmabhih': "Even a jeevan mukt can again come under the grip of worldly desires and start performing binding karm."
To become truly liberated, the first type of jeevan mukt has to conquer vidya maya, which is the original cosmic energy. This is not a creation of the mind, and thus it cannot be conquered through sadhana performed by the mind. This vidya maya is an eternal power of Shree Krishna and cannot be crossed by any means. However, if that jeevan mukt does bhakti and surrenders to Shree Krishna, then with Shree Krishna's kripa, he is freed from vidya maya. Then he is truly liberated and can never come under the effect of maya again. For as long as he remains in his body, he is called a jeevan mukt. When he leaves his body, he will merge into nirakar brahm and never be born again on earth.