If the weather remains cold, just save it. You will gain some benefit if once you get an inch of so of ice on top, remove the ice and toss it, the sugar is in the unfrozen part. You can actually repeat that a couple of times, each time throwing the ice away. However it you look at it and it's all frozen, save the ice, someplace in the ice is a pocket of sweet.
Another way you could do it, is to boil the 1.5 gal down to about a qt. and save that in the fridge until your next boil. It would be too difficult to reduce 1.5 gal to syrup without burning it in the process.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.