2 weeks ago I made 10 gallons of pickling juice for vegetables and only used 7 gallons. Today I decided to use the 3 remaining gallons of juice. I boiled the juice I made which was water, white vinegar, salt and sugar, and left it in the porcellan(spelling) pot that I originally boiled it in. The juice will cool down, and I will pour it into the glass containers with the vegetables. Is this juice still safe since it has sat out for 2 weeks (covered), even though I have boiled it for 5 minutes or should I just throw it out and start all over again. As a footnote, the pot is in great condition, no rust marks, it is all white, and the taste of the juice was fine before boiling.
Tl;dr - It recommends reusing brines only for fridge pickles. Since you have already heated up yours to make your original batch, heating it again (and processing it) may change the acidity and make it not shelf-stable. Since there were no vegetables placed in it, it may not have changed the acidity that much, but better safe than sorry. FWIW, I made a batch of fridge pickles with leftover/misshapen scraps, and I liked them better than the pantry pickles.
I can't imagine it has enough sugar in it to counter the acidity/salinity, but if you aren't sure, toss it.