All sources are available in the void-packages repository and are used by 
xbps-src, which is the
utility that compiles the code (if applicable) and generates the binary 
packages required by xbps.

You can rebuild easily all your packages with xbps-src:

 1- get a list of pkgs that were installed manually (not as dependencies): 
xbps-query -m
 2- build all pkgs set on that list with xbps-src: ./xbps-src -N pkg <pkg>

...