You can only get free refills at the resort you are staying at, not at any of the parks. We always purchase the mugs, it saves money and is much more convenient. If you just want to run into the food court for a quick soda or your morning coffee you can just go in, fill the mug and leave. You do not have to stand in line to pay. They make nice souvenirs as well, we have a cabinet full of them and use them a lot at home.