My peaches are ripe so I am making peach butter. The recipe I am using says to slowcook them in a crockpot for 6-12 hours on low with the lid half off. Well, after 12 hours, they still haven't reduced by much so I have cranked it up to high, removed the lid and am impatiently waiting for this incredibly good tasting soupy mixture to thicken. Any advice? Please?