I really need to just go ahead and buy a better mat. The one I've been using for my cutting was already designated once as not suitable but it landed on my cutting table when I needed one I didn't care about any stains from a particular craft project.
I've gotten really good at replacing my needles/seam rippers/sharp things as soon as they bug me -- except for rotary blades. I'm still working on my thought processes, buy in bulk when on sale and replace far more often than I do. Blades might seem expensive, but compare $5 for a blade to $100+ for your fabric, plus a premium on your time and frustration. Blades are cheaper than I am... just gotta get it into the routine a bit better.