Hit legs hard, it will help you retain size all over. Last year because of an elbow injury I could not really lift upper-body much, but did hammer my legs. It was pretty interesting because I didn't really lose any size up top.
You could also try doing some sprint training. This will stimulate fast-twitch fibers in your whole body, without stressing your wrist. I've known sprinters who don't even train upper-body in season, yet still retain a high level of development there.