Motivation is a very good question and the answer is I don't know. Anneinside has a good point...help with organization. Also, I know I tend to feel overwhelmed by something big (like I'm applying for grad school....well I'm supposed to be). So help her break it down into smaller manageable pieces.

I'd also add to ask her how she feels and what she would like you to do to help. She may have the best advice. I know I don't like being left out of the loop. Perhaps a checklist with things broken down or a chart or something. I personally like to start with something that gives me visible concrete results (because it gives me a bigger sense of accomplishment) before moving on to something more abstract with less visible results (which makes me less motivated to do). In a non-school related example I'd rather do the dishes than scrub the sink because a big pile of dishes gone from the sink is more satisfying to me than a sink that's cleaner. There's a bigger visual sense of accomplishment.

Perhaps your daughter might be able to tell you what tasks she finds rewarding. Organizing her work according to that might help. I'd also make it clear that she will fail if she doesn't do the work. On the other hand sometimes I find if I give myself permission to fail it removes anxiety and then I can carry on.

Perhaps organization by level of importance. Look at the syllabus for the class and see what is the most important and what she can slide on and still pass. I'm not saying she should skip all non-essential assignments but every now and then letting one slide might relieve some pressure on her. Make sure she knows you will love her no matter what. I hope that's helpful and sorry for being so long winded.