Unfortunately no. The hardner has to be thouroughly mixed to due any good. The milky problem was probably caused by moisture of some type. Usually, in even cold climates epoxy will eventually cure as long as it's not too cold. the only thing you could do now other than sanding is give it lots of heat and pray. there's nothing worse than romoving soft rubbery epoxy. You usually have to scrape it off. Make sure you test whatever epoxy you use in the future. My suspicion is that you mixed the ratios wrong, too cold & moisture or a combination of the two.