Something I was told when I ws a kid shooting them in the neighborhood with a pellet gun. When you spook one, and he is running, blow a whistle. Many times, rabbits will stop, and look aroundto see what that was. I don't know why they do it, but it always worked for me.

2) when you, or the dogs spook one up, you can always just stand your ground Rabbits have a habit / instinct to run a circle back to the start point. If you wait a few minutes, good chance that floppy eared cottontail will come right back to you.