Hopefully, you're not lying on the couch this off-season.
The off-season is a great time to recover and focus on new activities. This post from Gale Vennare on www.active.com makes complete sense of key areas of focus for the off-season.
During the off-season, strength training is fabulous. You also need to maintain your balance. Keep activities up to a point where you are not breaking yourself down, but you are maintaining the edge you developed in-season.
Remember to consider your diet. With not being as active as you might be during the warmer months, athletes need to be more considerate of what they consume.