As far as I know the best juices to drink to cure a stomach ulcer are potato and cabbage juices. I am not an expert in advising something but I would recommend for ur friend first to cure her ulcer by eating properly healthy food and in right combinations plus freshly prepared juices at least ones a day (based on ulcer curing juices mentioned above). No one medicine can help healing an ulcer but healthy eating in the real sense of the term. I would recommend her first to cure her health problem and then go for a liver flush.
Four years ago I had a stomach ulcer operation but I had my first Liver Flush yesterday (and again, I am not an expert, but i think it was poss for me coz all i have how is a scar but not an ulcer itself.
I read somewhere in fasting forum that even if a person has a stomach ulcer he/ she can have a juice fasting (dont forget including cabbage and potato juices). Go to a juice fasting forum and ask experts in it (Somer is good in it!).