Natural Reincarnation doesn't recall previous memories, as the soul is supposedly cleansed before reincarnating. Unfulfilled Karma do carry over, however.
I had a hunch, why her soul can be incarnated. I think it has something to do with Mu guy. Maybe a part of his soul gave it to huang yue li. So that's why on the day she was incarnated, that masked guy went to see her on that exact day.