Pick them up and hand them back. And no, that's not a joke.
When the dice (or a single die) bounce or fly off the table, the dealers usually rely on a customer to retrieve them. You don't have to be playing on the game. In fact, dice typically bounce a long way and are picked up by passersby. If you see one, pick it up and bring it back to the game.
The important thing is not to throw it onto the table. Rather, hand it to a dealer, who'll in turn hand it to the boxman to inspect.
Any time a die goes off the table, the main concern of the pit crew is that the same one gets put back into play and the boxman will always inspect it to protect against a "gaffed" (loaded) die being switched in. It's usually a cursory inspection, but they always check. Dice switching is something that casinos constantly have to guard against. An excellent account of techniques used by a successful dice-cheating team can be found in the book Loaded Dice –- The True Story of a Casino Cheat by John Soares.
If that occurs while you're shooting, don't worry about it. It only happens about 300 times a day in each Las Vegas casino.
Unfortunately, most gamblers are superstitious, and there is an old saying at the dice table that goes like this: "Dice on the floor, seven at the door."
Many crap players will call off their bets when dice leave the table and if dirty looks could kill, you'd be well on your way to Arlington National Cemetery.
To get out of this sticky situation, after throwing the dice off the table, simply say, "Same dice." That's what the pros do. You don't want to shoot with just any old dice; you want the same dice you were shooting. It's pure superstition, of course, but every seasoned dice player does it. No more dirty looks, no more worries about bombs in your luggage. Suddenly you're everyone's friend again.
Of course, there's absolutely no valid reason to call bets off solely because the dice have gone off the table.
Finally, if the dice fly far enough away, they could wind up being a souvenir for someone. We've seen a customer pick them up, put them in his pocket, and just walk away. It's true.