Last weekend I boiled 100g of caapi in water, for 2-3 hours 3 times and kept what I had strained from each boil. The tea has been sitting in the fridge, but I've left the rest of the caapi sitting in the pot, on the stove immersed in water for the past 60 hours or so.

My question is, will it still be okay to use the caapi to go for one more boil, or should I just reduce what I have in the fridge already and drink that?

It certainly wouldn't hurt anything but not at all necessary to boil 4 times for 3 hours.

If you want a little boost to your caapi tea put the now saturated vine in the freezer over night then reboil. This breaks open more cells structures and gets more goodies to get the last drop out. Or you can do this in the beginning next time.