No, rebuilding the mesh does not require taking any of the devices off the network. Quite the contrary.
It’s basically a one button push request that the hub run a utility which will start rebuilding all of the address tables by talking to each of the devices that are connected to the network. Well, one button push after you navigate to five layers of menus. Once you find it, It’s easy. Takes about 15 minutes to run, although you may not see improvements until the next day after all the changes of propagated. A lot of people run a repair once a week just for regular maintenance. Your devices will be unavailable for about 15 minutes but after that everything will run as usual.
The following will explain more. This is a clickable link:
And here are the official support instructions on how to get to that one button that you push to start the Z wave repair:
