So I'm no expert, and I'm also not a bedwetter (although currently debating whether I should legitimately train myself to do it). It seems to me that you'd want to increase fluid intake before bed. What you're trying to do is re-train your body to "release" when it gets the signal that your bladder is getting full. If you drink right before bed, you're making sure that your bladder will fill enough to signal that it's getting full, and you can wake and wet and go back to sleep without issue... that'll train your body to do it for you. If you don't drink before bed, you run the risk of your bladder not filling enough to signal "hey I gotta go", so you run the risk of sleeping through the night without wetting. I know if I want to practice wetting at night, I chug a glass of water right before I crawl into bed. That'll guarantee that I have to pee in the middle of the night, and when I wake up I just fill my diaper without getting out of bed, and then drift back to sleep.