In what ways is the the mat not standing up? Is it your cuts are impacting the mat? Is it the mat warping?? How long have you had the current one? With hard use you should still get a couple years at least.
I know when I'm at friends with the large mats that I particularly dislike the hard shiny white?/clear? one. I feel unsafe, that the blades slide dangerously on the surface and that they dull my blades. I like the self healing style. Cutting lightly with fresh sharp blades beats cutting hard with dull blades which also wears both on us and our mats and our fabric as well.
I'm a big believer in not using the grid side, and prefer to use a standard Olfa mat, grid side down. If you use the grids instead of your rulers, you will tend to cut in the same area of the mat for a variety of reasons, with pretty much all of your wear centered in one area and the corners perfect and whole. The repeat cuts can make grooves that allow threads to be skipped, and eventually shatter/break along the lines. I also like the Fiskars and Sullivan self-healing mats, but those typically are printed on both sides.
That's a pretty huge mat size, can you possibly use two smaller mats instead? I have two 24x36 mats on my large cutting desk, but I usually use a space smaller than a standard 18x24 for my actual cutting, and for my block trimming I've started using a rotating mat more and more.