The biggest problem Dean (and the Democratic party in general) could face in this debate is another series of horserace questions. What Dean and every other candidate there needs to do is if they get asked a horse race question, to respond by ignoring the question, and instead talk about one of their favorite issues.
This clearly most important to Dean who has to get "back on message." But it is also important to the rest of the field to remind voters how politics are relevant. Otherwise the democrats risk becoming a miserable failure.