Chris, when dealing with transfer students who need to return to a lower level, I generally explain that since they've been away from lessons for a bit, review of former material is wise, and something everyone does, and as they are obviously good students, I expect that they will move very quickly through it. I use a method set for this which is different than what the student used originally, and I also tell them not to get hung up on the level number, since level 1 in one set may well be a level 3 in another. Surprizingly, most students are actually okay with this and we get through the review rather quickly in most cases. Often, I make a game of it, to see what the student can remember, when it's fun recall rather than a dull listing of facts.