Unless you live in a really warm climate the wakeboard season is not a year round event so there is some downtime until the weather warms up. You can extend the season with wetsuits and other gear that will help ward off the cold, however once the water temperature reaches a certain degree you risk hypothermia and that quickly removes the fun factor.
So what is a wakeboard fan supposed to do during this time? The answer is keep yourself in shape and learn how to be a better shredder.
There are several different exercises you can do during the off season that will keep your body in shape and there are 100's of videos that will increase your knowledge and give you new ideas to try with the water warms again.