According to my Houseplant Expert book, Cyclamen will bloom for several months and then take a rest. Sounds like you've been doing something right to get it to flower so long. The book says it will rebloom after a rest period. Here's what my book says in the "secrets of success" section:

Temperature: Cool .. 50-60F is ideal.
Light: Bright light away from direct sunlight
Water: Keep moist at all times
Air humidity: stand plant on a pebble tray or surround with damp peat. Occasionally mist air around the plant
Care after flowering: Reduce watering and stop feeding. Place pot on its side in a cool spot and keep it dry until midsummer. Then repot using fresh soil, burying the tuber to half its depth. Stand the pot in a cool, well-lit spot. Water to keep moist.

So I think the book is assuming you buy a flowering pot in winter and get a few months of bloom, and that's why it's suggesting "keep it dry until midsummer" which is probably a three-month period. Perhaps in your case bringing it out in December would work. Full winter sun is so weak that you could probably put it in direct sun at that time. Battling dry winter air might be the tough part.