When you do get her, it's not magic that's going to make her stay. Magic can help bring a person back to you, but human nature shines through magic when it comes to spells. What's going to make her stay is either:
- Deep within herself, she's going to want to.
- The circumstances that brought her to leaving in the first place have been fixed / changed.
So I would focus first in bringing her back. Work on whatever issues you two have. Work on your half. Be introspective. Write it out. Think really hard about what it is that isn't working between you two now. And while you're doing that? You can maybe try using a moving candle spell, where you bless both candles as you and her, and move her candle towards you every night (or morning), focusing your intent on drawing her back. Start a honey jar on her, if you don't already have one.