RE: u shot, you missed, what would you do next?
I would mentally mark the spot where the deer was standing when you shot, climb down and go to that spot and search very carefully for hair and blood to make absolutely sure you didn't hit it. Sometimes deer will do strange things when hit, including no reaction at all, and you owe it to the animal to make sure you really didn't hit it.
Once I was sure, I would probably get back on stand or move a few hundred yards away and continue to hunt. During the rut, you should be in the woods as much as possible... ya just never know!
WHen I got back to camp, or home I would take the first opportunity to shoot a few rounds at a target to make sure you didn't bump your scope. (some practicing wouldn't hurt either)!