What may be defined as failure to you may be utter relief to her. And if you are more invested than she is in keeping her in college full time away from home, she is going to continue to need rescued. Believe me, I'm speaking from experience. IF it can be fixed so that she can return and have another chance, I think the conversation that might be the most helpful is the one where she feels just as safe saying it is too hard to go back as it is to say she wants to try again.
My daughter was diagnosed with ADHD this year after losing her scholarship and killing her GPA. She has decided to continue to go to college - on her terms. She is only going part time while working part time. And for her, it has finally given her success - on her terms.
I'm not saying you shouldn't help her get the help she needs, but if she isn't in the driver's seat on this, she'll continue to fail and you continue to rescue and push her forward,
Then again, this is only my opinion, and I could be totally wrong,