Chris look at your contract and see when you had to get a response. You may already be out of contract as the the response time from lender to remove the seller contingency often puts them out of contract. There is not one thing a buyer can do to shorten the time that a lender take to respond on a short sale. That is in the hands of the seller and the listing agent.

If you have a Realtor working for you make sure they are experienced in working with short sales. Every bank has a different response time base on their own "red tape". Since I don't know how far along in the process you are, I can't tell you if you can cancel your offer.