Big publishers will consider republishing books if they believe the book is timely and has untapped potential – but you have extra submission hurdles, the biggest one being the low sales numbers in bookseller databases. Booksellers aren’t likely to pick up a low-selling book a second time even if it’s got a different publisher. You have elbow room if part of the problem was that the book didn’t get into bookstores in the first place. The positive reviews work in your favor. Ask your publisher to revert the rights back to you; your contract should have a clause explaining how to do that. In your pitch to new publishers, explain the circumstances of its low numbers and present a case for why you’re able to help promote the book more heavily this time. If it’s a picture book, you need the artist’s O.K. to re-shop the book and s/he must get the illustration rights reverted. Or you can shop just the text, to be re-illustrated. Your new house could then pitch this as a new frontlist title instead of a reprint or republication, giving it a fresh lease on life.