One option if you didn't have access to toads/frogs during the coldest part of the winter would be to brumate (hibernate) the snake until the amphibs come back out. It would be easy enough to do, especially since the snake is wild caught and has already brumated at least once. Just begin dropping temps gradually over a two week time period in late Sept/early Oct. By mid to late Oct, temps should be between 55 and 65 F. Keep plenty of fresh water available at all times, but keep it dark for the snake and cool. Try not to let the temps drop below 50. To achieve these kinds of temps, you may be able to place the enclosure in a closet, attic, garage, etc. Just depends on your situation. Then by about Jan or Feb, when you start hearing frogs calling, gradually raise the temps over the same time period as you used to lower it. After a week or two at normal temps, the snake should go into a shed cycle, after which you could begin feeding again. Brumating like this is necessary in breeding most US colubrids, but also really helps with snakes like this that prefer certain prey items not available all year.
-Chance