It doesn't take long before the rabbits will become comfortable with your tactics, so you've got to try lots of different things in rotation. You can try whirligigs and wind-powered wood tappers. The scent of human hair and predator urine (fox urine, specifically) will scare them off. Blood meal is a deterrent, but it is pretty much pure nitrogen and you've got to be careful not to get it on your plants. Still, it offers good short-term protection until your plants are up and beyond the tender tasty morsel stage.