any awards / noteable critical praise, sales figures if relevant, how long the book was in print for, placing on any bestseller lists, or any 'best of' 'editors picks' etc at industry publications or chain bookstores.
Also it might be wise to indicate why your old publisher didn't want to reprint the book/renew the contract. Be honest with teh new publisher though if they ask outright. If your publisher went bankrupt for example, then say so. Or of it's a book that was in print 20 years ago and at the time you never thought about a reprint then say so too.