Shocking won't do anything for your plumbing except for the air that may get in the lines. Air can shake things up and knock loose a lot of minerals that have built up over the years. The problem with that is that your plumbing gets smaller as it heads toward your faucets. This can cause a total blockage sometimes that can be very difficult to break loose.
You could replumb the house, or maybe just the main lines that are easier to get at. Especially any old galvanized pipes. They plug the fastest.
If you could run air backwards from the faucets to an open pipe near the tank, that would clean the pipes some and hopefully not plug anything up.