i use the Xryon repositionable cartridges refills. I clean the mat first with soap and water to get the majority of the fibers off the mat, then let dry. Take apart the cartridge and just place the sticky stuff on my mat, and then peel back the white backing.
I use the little X refills, as they are the cheapest. The restuck mat lasts a long time. Just make sure it is the repositionable ones!