Short sales are subject to 3rd party approval, because of this, as a buyer you are "at the mercy" of the seller. Short sales tend to be long drawn out affairs because first the seller needs to be approved to even do a short sale and then the offer needs to be approved. If you really love the place hang in there, it can still close. If none of the terms have changed between the time of the expiration of the first approval, it shouldn't be too much of a problem to get approval again. Ask your Realtor what the contract states but as far as your "rights," it should say in your contract if you can back out or not if you are not pleased. Always check your contract! Hope this helps, best of luck.