I'm glad that you are posting this question. Being 13 is very difficult as it is without having to deal with this sad news about her father. I don't know much about his condition, but I would expect there is a good chance he will not improve.
Teenagers often have not yet learned coping skills that adults may have learned. It would probably be helpful for her to have a counselor. This would give her somebody to talk to and a way to help process her feelings.
Any time that the two of you can spend together would be great. Do you like to go for walks? Maybe the two of you could take a daily walk together where you can just spend quality time together.
If she doesn't have a journal, she could probably benefit from having one. It helps teenagers and adults if they can write down their feelings.