You can purchase a water park annual pass for $99.95 plus tax. If you wanted to upgrade your current pass so that it included waterparks all in the same ticket, you would need to upgrade to the premium annual pass, which costs about $200 more than the seasonal pass you have. So it probably wouldn't be worth it to upgrade the seasonal unless you also wanted to visit Pleasure Island, Disneyquest, go to the parks on the blockout days for the seasonal pass, etc.