I was using my mat as suggested by Cricut, to roll the mat to remove the paper so that the paper didn't curl. Well, the paper didn't curl, but my mat cracked.

 
this is the back of the mat

I can still use the mat in different areas and work around the crack. The mat wasn't that old and I wanted to get more life out of it. I heard of others who had used packing tape on the back of their mat that had cracked to get it to last a bit longer.

So I gave it a try. And yes, it does work. The packing tape holds that mat flat and I can continue to use that area of the mat. I know it won't last forever but I am happy to get a bit more life out of my mat.