“You can’t repeat the past.”
“Can’t repeat the past?” [Gatsby] cried incredulously. “Why of course you can!”
This exchange between Nick and Gatsby serves as quite direct evidence for Gatsby's intentions of recreating the past. Though his one friend, Nick, challenges the presumption that this is at all possible, Gatsby nonetheless persists.
Recreating the past is part of his chivalry, part of his ideal, and part of what he sees as his destiny. Gatsby's rather innocent vision of the possibility of recreating the past is related to his innocent vision of himself. He is the quintessential dreamer, bent on fulfilling a vision and refusing to doubt in the validity and the possibility of the dream.
To achieve his ends, he will force Daisy to divorce her husband and go so far as to demand that she say she never loved Tom. This Daisy refuses to do, but Gatsby's demand is proof in itself that he is not content to claim Daisy as his own but must go further. He must claim Daisy's past and render things new again.