After reading your file, I'm not sure what can be done to undo what's already been done.  I think a better solution would have been to reduce the assessments for everyone for the upcoming year(s) until the excess has been used up.  Maybe the way to correct it is to reduce upcoming assessments of those who should have received the refund and didn't, and calculate how much is owed back by those who received a refund who shouldn't have, and keep their assessment where it was until they have paid back the difference.  But the math could be kind of complicated, and I don't know what your bylaws allow when it comes to re-calculating assessments.