Dismiss them for the day, or the portion of the practice you are currently on. No need to even raise your voice or get upset. The message gets across quickly...
I don't like running as punishment. Sometimes you have to bark to get their attention, so maybe that's an option - just make sure it's done objectively and impersonally.
Your only real tool is the bench. If you don't bench your players, they will never perform for you.
Games: Have a defined set of expectations about how they are to play the game. If any kid doesn't perform, sit her on the bench. Reward kids who play correctly with more playing time.
Practices: The problem is most likely with your practices. My guess is that they are too slow. You have to keep them moving.
Punishment running is for dictators. You want to do conditioning, then do conditioning. You want to get the message across that laziness will not be tolerated, it's the bench - AND THAT INCLUDES YOUR STUDS!
It's hard to use the bench when you don't have a game for 3, possibly 5, months.
My oldest DD is entering her 3rd year of travel ball (2nd year 12U) and she has a new coach who will make them run a lap (indoor practice space which is an old airplane hangar). At practice the other day, after she made three bad throws in a row, down around her partner's knees, he told her she'd be running a lap if she made another bad throw. She corrected herself. Her old coach would never do something like this for any reason, so this is kind of new to me and I'm not 100% sold on it, but I've seen at least some evidence that it can work. He's also run the team for talking, goofing off etc.
I coach my younger DD's 10U team and we often have a local D1 player come help us out. She doesn't mess around and she'll have the girls do push ups. She's not mean about it, but she is no nonsense and the crazy thing is, the girls seem to like it.