Depends on if they were measured before freezing or not. Say a recipe calls for 4 cups of fruit. If it was measured and frozen as 4 cups then you would need it all. That's why freezing in measured amounts is recommended. If it wasn't measured first there will be lots of extra juice and it may not set as a result without at least some draining.

I'd suggest draining it but keeping the juice and adding very small amount of it back to the mix as needed as it cooks. Once you do your freezer dish test to check the set you can then add a bit more if needed.

Dave