If you are not able to get the message across to her about how serious this is, is there someone else? A family member she is close to, a boyfriend...? That person can either sit her down and have a serious chat (I don't know her, but it sounds as if the kind and caring route has not proved fruitful at this stage) or take that person away from her life until she submits and co-operates. The moment she takes a step in the right direction, reward her with something that means a lot to her.
I know the feeling of wanting to stop meds as they either make you feel numb or very tired. She needs to understand that a lot of this can be overcome by cooperation with the pdoc to get the right combo.