Hi Ronsputin and welcome to EAB!
You can use the same disk again and different slots for your games. Just click on another slot to the left once you clicked on save. You could also use WinUAE's savestate feature to save your game. Press F12 ingame and go to the 'Miscellcneous' panel. There you find the buttons 'Load State...' and 'Save State...'. Might be even a bit more convenient this way