Here is a tip I found on the Cricut message board. I have tried this and found it works great.
ZIG 2 Way Glue - Jumbo Tip
Using an old rag and alcohol, rub mat until all sticky is removed. Very easy process! Rinse with warm water - let dry completely. Finish by applying ZIG 2 Way Glue to entire mat. Whip away any glue on the green outside edge. When glue turns white (clear) replace protective sheet. The mat is now sticky and ready to use.