Michelle, it is better to take your losses in the fall than to put the effort into overwintering a weak hive only to have it fail sometime during the winter or spring and surrender the equipment to moths and mice. Fall is just around the corner. I lost two weak mating NUCs over last winter that I should have combined last fall.
My focus now is to get colonies ready for the winter -plenty of food reserves, low mite counts and healthy, young bees entering the fall.
The best hive I ever had resulted when I combined a queenless hive with another, which went on to make 11 gallons of honey the next year. :-)