Your moisture mat is just there to encourage your worms to work in the surface of the waste and as it is biodegradable the worms will eventually eat it. If the moisture mat is disintegrating quickly you can add more waste.
Looking to get started with Worm Composting or for some bits and bobs to keep yours running happily? Pop on over to https://www.wigglywigglers.co.uk/collections/worm-composting
P.S. It's always the right time to get that old wormery up and running, order our rescue kit for everything you'll need (and instructions) https://www.wigglywigglers.co.uk/products/wormery-rescue-kit