Finally it was TALKED out. Unless the story can offer a good explanation as to how Aster can turn back time but not give up her soul or be reborn again, then I don't want her to come back. Equivalent exchange is established now. I don't want it handwaved away!
Personal theory based on the stated facts that:
1. The body and soul are separate (even if she literally give birth to the same body doesn't mean it'll be the same soul)
2. Magic affect only things that physically exist. (magic can't affect souls)
3. Magic power is somewhat hereditary (Schderl thought Lihen was a descendant of a wizard due to her having magic)
My vote is that the protection of time on Lihen either contain the actual soul or some kind of duplicate data of the daughter, and when Lihen have a child the magic inherited will pass along the soul/data into the baby.
Back in ch 1 she said "No matter what changes, I'll still be mum and dad's child" and that bubble was highlighted...