I know of a few applications that have a "Redo" button, but sadly, none of them are drill design software.
I had a though a while back about using something like the Razer Naga (which is a gaming mouse) for design, because there are buttons on top of buttons. That way, you can just hit the button on the mouse instead of moving it up there to hit a command. Someone is using one now and they love it that way, so I'm going to get one at the end of the month. This would likely be the best solution until a redo is going to be placed into Pyware (and then it can be mapped to the Naga).
The Second Drill Design Exhibition is below. Give it a whirl and see what you can do:viewtopic.php?f=4&t=5232