Faustus' character experiences some degree of change over the course of the play, but crucially not enough change to save him from his terrible fate.
Initially, Faustus is a restless man, deeply dissatisfied with the limits of the human intellect, despite his vast learning and erudition. Hence his fateful decision to sell his soul to the Devil in return for twenty-four years of power. Yet even once this power has been granted, Faustus remains unsatisfied. And no wonder. Throughout his various adventures, he often comes across as more of a glorified entertainer than a wise man penetrating to the secret depths of creation.
As the end of his twenty-four years approaches, Faustus starts to turn his mind toward the one-way journey to hell that soon awaits him. He starts to contemplate the terrible fate that lies in store for his mortal soul. No longer the arrogant scholar we met with at the start of the play, Faustus is genuinely frightened and nervous as he starts to realize just what a bad deal he made with the Prince of Darkness.
But although Faustus has undoubtedly changed by the end of the play, it's clear that he hasn't changed anywhere near enough. It's notable, for instance, that instead of getting down on his hands and knees and begging forgiveness from God, he makes his supplications to the Devil instead. In other words, Faustus' new-found humility is pointed in entirely the wrong direction. This is a man who clearly hasn't learned his lesson at all.