Hi, N.. I haven't had any experience with Lupron, but my gut tells me that if her ultimate goal is to have children, and if it would devastate her to cancel any plans to get pregnant, then it makes sense to at least try drug therapy before surgery.
From what you wrote, it is not clear whether one ovary or both ovaries are causing the problem. A woman can still get pregnant with one working ovary, so if the drug doesn't work and they have to remove one, just one, then she still has a chance at pregnancy. It may take longer to conceive with just one ovary, but it is certainly possible. The normal fertility cycle involves just one ovary each month -- alternating between left and right. She still has a few possibilities in front of her.
I hope the drug works, for her sake, because surgery is painful and she will have to adjust to a different hormonal cycle if she loses one or both ovaries. Please let her know I will say a prayer for her healing and ultimate motherhood.
Peace,
Syl