How does darcy respond to elizabeth's refusal?

In the short term, he tries to defend himself, in a letter to Elizabeth.

In the long term, he reviews his approaches to life and his attitudes towards others. We do not see him doing this, but we do see the effects. For example, when he proposed to Elizabeth, he spoke of the various problems with her family, making her an unsuitable match for him. At the end of the book, he has learned to respect her family and says so.