Every state has different WC laws so you would have to check with your state or your insurance company. I do know that a lot of WC policies are based on the amount of the payroll, with a minimum to be payed. So you probably wouldn't get a refund if your payroll for the year is under the minimum. If you payed more than the minimum and your payroll was under that, then you would get money back, assuming your state works like this also.
Call your insurance company tomorrow and ask them.