The key to fixing this is adjusting your landing zone. When the greens are softer, you need to make sure that - if you take the same club as normal - you land the ball closer to the pin as shown by the red circle, due to the fact that the ball simply won't roll out the same distance as it would in the summer (as shown by the blue circle).

Alternatively, you could take a less lofted club and keep the landing zone the same - the lower loft will ensure the ball has more roll out on the green. 

These tips will have you making more up-and-downs during the winter, ensuring your handicap continues to drop along with the temperature!