The frustrating thing with this scenario is that often the lenders are in no hurry to meet deadlines are could care less. The employees are clock watchers and the sense of urgency that we deal with and our clients expect is lost in the "your time is important to us" and the "we appreciate your patience" nonsense that is routine in the 9-5 "cubicle city".
I know of a short sale in Suwanee right now that has taken 2 months for the bank to accept the offer.... they are waiting for something better to come along which is probably the case on the home you placed the offer. WIth that being said, I would keep looking for something better to come your way until you know that the short sale offer is accepted and it is accepted in writing.
If you want the home, "dot the i, and cross the t" - put in another offer, but with a longer period. Talk to your Realtor about an acceptable time frame since each home is different. NEVER do an open ended contract, unless you NEVER plan to purchase another home. Actually, you could "officially" remove the offer with another form, but in practice, it's not good to leave it open-ended like that.
In the offers I described handling from your earlier questions, all the deadlines had passed before we got responses. You probably do not need to submit another...but it would not hurt to send one with a long deadline just to show that you are still there and still interested.
See if your agent can find out from the other side if all short sale conditions/requirements have been met by the Seller and all documents required from the Seller have been submitted to the lender. That may be what is holding up a response to you.