I think it's obvious that your recipe has to change if you are having complaints about the product being too dry when reheated. The microwave is taking the little remaining water and using it to cook the product but in doing so the water level remaining within the product is so low it's thicker than your customers want it to be.
Basically you need a higher level of retained water in the food before it's microwaved... Tony was suggesting that the easiest way to do that would be to... add more water. There are other ways like looking at the other ingredients to see if any of them are reducing the product water content more than you need and reducing that instead. That could be a stabilizer or some of the other dry ingredients.