How did Lord Krishna revive Parikshit in Mahabharat?

How did Lord Krishna revive Parikshit in Mahabharat? Lord Krishna saved Parikshit because he was not destined to die. Krishna does not interfere with destiny and hence he did not save Abhimanyu or Draupadi's sons. But Parikshit was destined to live and rule the Kurus for a long time. Krishna challenges Ashwatthama that he will save Uttara’s son Vasudeva replied, “This supreme weapon is invincible and will indeed descend. The foetus will be born dead. However, it will revive and live till a long age. O extremely evil-minded one! That king will be known by the name of Parikshit. O worst of men! You will look on. Behold the power of my austerities, energy and truth.” 16, Aishika parva, Mahabharata. When the Pandavas had went away to Himalayas to collect the hidden wealth of Marutta, Uttara gave birth to a dead child. Great lamentations happened in Hastinapura. Draupadi, Kunti, Subhadra and Uttara pleaded to Lord Krishna to save the child and the lord agreed. Lord Krishna invoked various truths and withdrew the power of Brahmashira, allowing Parikshit to come back to life Krishna touched water and withdrew brahmastra’s powers. Dasharha had promised that he would bring him back to life. The one with the pure soul spoke these words, so that the entire universe could hear. “O Uttara! I do not utter a falsehood. This will come true. While all the creatures look on, I will revive him. I have never spoken a lie earlier, not even in jest. Never have I retreated in battle. Therefore, he will come back to life. I love dharma and I specially love brahmanas. Abhimanyu’s son was born dead. But let him revive. There has never been a conflict between me and Vijaya. Through the virtue of that truth, let this dead child come back to life. Since truth and dharma have always been established in me, let this dead child come back to life. I killed Kamsa and Keshi by resorting to dharma. Because of that truth, let his child again come back to life.” 68, Ashwamedha parva, Mahabharata. When Parikshit was brought back to life, everyone praised Krishna ‘Krishna thus withdrew the power of brahmastra and that room was illuminated through your father’s energy. All the rakshasas were rebuffed and forced to leave that house. An invisible voice was heard to speak in the firmament, “O Keshava! Excellent.” The blazing weapon returned to the grandfather. O lord of men! Your father again got back his life. Appropriate to its capacity and its strength, the child began to move. O king! At this, the Bharata women were delighted. On Govinda’s instructions, the brahmanas pronounced benedictions. Everyone was delighted and praised Janardana. The wives of the lions among the Bharatas were like those who acquire a boat and reach the shore. Kunti, Drupada’s daughter, Subhadra and Uttara and the wives of the other lions among men were cheerful in their minds. Wrestlers, actors, fighters, narrators, soukhashayikas and large numbers of bards and minstrels praised Janardana.