I use the following drill to sharpen up my responses when standing up. Put up stumps (even 1) and have someone throw a ball on the bounce (not very hard), and practice taking the ball. Then place a chair to simulate the batsman and have them pitch the ball in between the legs. So when you are standing up, the ball should disappear inflight for a bit then reappear on the other side. After you get used to that tell the thrower to impart some gentle spin so the ball will deviate a bit in either direction. Randomize this as much as possible. Couple of things this works on, one is staying down as long as possible so that you can rise with the ball. Second is to get your hands and feet moving even with unpredictable bounce or view being hindered by a wondering batsmen. Sounds a bit silly but it works, I use this to practice for any around the wicket bowlers and the spinners. Btw this is not my invention, picked it off some website or book, so credit to whoever it is. One caution is, not use good chair, you will break it. Now I use a plastic chair