Freezing the fruit might result in a bit more juice extraction since most of the fruit would self macerate. Letting it sit on some sugar for a couple of hours would then get just about all of it out. Of course some water would still need to be added more than likely.
What color was the mold? White and slightly fuzzy, like velvet, or some other color? Did it look something like this?
The image is of koji. Koji is the mold that breaks down the rice so that the yeast can metabolize the sugars. Not sure how you can make sake without mold.