Over twenty years ago when one of our children was 6, and wetting the bed sometimes 3 or 4 times at night, we had great and fast success with an inexpensive device called the Palco Wet-Stop Alarm Device. It is still available, because IT WORKS!
Ours was small and attached with velcro to the pajama shirt shoulder, near the ear with a small wired sensor that fit in a small pocket on the child's underwear. It buzzes at the first drop of moisture. The first night it woke everybody in the house EXCEPT our child! That is how soundly he slept! We woke him and followed the directions. It teaches the child to notice what it feels like when they need to get up and go to the bathroom.

It even came with coloring pages and teaches the child not to sleep so soundly, that he's unable to feel the urge or hear the buzzer. I reminded my son frequently not to sleep so heavy or so soundly that he couldn't hear my voice if I called his name at night. There are other obvious safety reasons for this also. TEACH the child to have this control.

Our child had success in a week, as well as my 6 year old niece, but we continued the alarm for 3 weeks as recommended. Only once did he ever wet the bed again and I simply reminded him not to sleep so soundly. Explaining and teaching this has helped some of our foster children even without the buzzer.

I would eliminate all carbonated beverages but don't restrict fluids; their bladders need to stretch and grow and they could dehydrate. Anyway, the bladder empties no matter how much is in it when a child allows himself to sleep so soundly, sort of like when under general anesthesia, is what a doctor told us. That is why our child wet the bed as many as 3 or 4 times a night before he learned to sleep lighter.

The product package seems to have improved, now, with a different magnetic attachment instead of velcro and a book on CD and calendar and stickers instead of coloring pages. Everyone I've recommended this to has had success.