She has already had a hard enough time dealing with the consequences of an accidental pregnancy. She may even be punishing herself because she feels foolish for having gotten pregnant in the first place. What she needs to know from you is that you still love her and accept her as your daughter. Don't expect your daughter to forget the whole thing ever happened. Don't expect her to stop talking about it or thinking about it right away.
Many women return to their normal selves again almost immediately following an abortion.
If not, watch for signs of depression. If she starts dwelling on negative feelings and thoughts, do help her remember why she felt an abortion was her choice. Remind her that she did the best she could in a difficult situation. Give yourself credit for standing by her when she needed you most. Do understand that after an abortion, your daughter's hormones will readjust from a pregnant to a non-pregnant state.