Use rubbing alcohol to clean your cricut mat. Just pour a little on the mat rub it around and take a rag and wipe it off. Take the mat and wave it in the air and dry it and it will be sticky!! I did it twice took me a min!!!!!!!!
Here is a video showing how I make my Cricut mats sticky and reusable again! For a complete write up with more details including a few extra tips: http://www.hidinginmycraftroom.com/2010/08/making-cricut-mats-sticky-again.html Aleene's TACK-IT over & over