dpkg-reconfigure [options] packages
dpkg-reconfigure reconfigures packages after they have already been installed. Pass it the names of a package or packages to reconfigure. It will ask configuration questions, much like when the package was first installed.
If you just want to see the current configuration of a package, see debconf-show(1) instead.
Note that if you normally have debconf set to use the noninteractive frontend, dpkg-reconfigure will use the dialog frontend instead, so you actually get to reconfigure the package.
Joey Hess <email@example.com>