I would have to ask her why she keeps bringing it up? Is she wanting you to agree or disagree?.. I'd always respond with "Yea, I remember you said that the last 2 (3,4, or 5) time(s) we talked.

I HATE people who keep repeting the same things to me like I didn't get it the first time they said it, or the second, or the third. It's like beating a dead horse to death!