Unlike the older installers of yesteryear, Command Center doesn't allow you to re-install
just the Sonitus effects separately (like you can with other effect bundles such as the Engineering FX Suite), but they are part of the basic SONAR install so you should be able to re-install SONAR and get them back.
Unless...if it's an old project that used the DX versions of the Sonitus plugins, then you'll have no choice but to replace them with the newer versions.