Turn melted sugar back into granular?
You probably can't achieve the size and uniformity of classic granulated sugar at home, not without finding some special equipment. But if you are OK with other crystal sizes, it is very simple. 

All you have to do is to search for recipes for rock candy. It is nothing but re-crystalized sugar. Also considered to be the easiest candy to make, you'll find it in many "cooking with children" books and blogs. 

The one problem may be that you are not crystalizing sugar, but a combination of fruit juice and sugar. If the juice has enough acid to invert your sugar, it might not crystalize well. You'll have to try and see.