Contract Help - Unknown probate issue

[Alex Powell]

I recently got a house under contract for a single family home. We discovered the house is in probate and will take some time to be resolved, therefore we won't be closing on or before the date specified in the contract. Now the seller wants an additional $10,000 added to the purchase price we originally agreed to. Can I stand my ground and say no to the additional $10,000? My worry is that if I say no to the purchase price increase, the contract can be voided because the closing delay due to probate. Does "Specific Performance" come into play here?

I'm using a standard AS-IS Florida Realtors contract that can be found online with a quick google search. 

Any help you can provide will be greatly appreciated.