I use more juice to carb my bottles of cider. When it comes time to bottle I will add in another .5-1 gallon of juice (might be more cider or blueberry or any other flavor you can get your hands on) I let the sugar from that carb my bottles as well as add back some sweetness/flavor.
So my list...
I made a batch of this and I LOVED it. I will be making it again for sure.
For people wondering how many watermelons to buy, Usually 1 will do. I got roughly 7.5 cups from a medium sized one.