Give a Slow Down Cue
Sometimes dogs are running so fast, that they just skid off the table. If that happens in AKC you are immediately disqualified.
So train your dog that he has to slow down a when approaching the table so he doesn't slide off.
This happened to Magic Momo in a Fun Match. She was running super fast and slipped right off the table. But she learned her lesson and that hasn't happened again. You can see dogs slipping off the table in the "Funniest Dog Agility Bloopers"