ReloadUI

From WoWWiki

The Cosmos AddOn ReloadUI

This allows you to reload your interface with

/rl

Reloading your UI without AddOns

You can also reload your UI with the command

/console reloadui

which doesn't require any AddOns installed to work. Reloading your UI will purge the UI-Memory and load all AddOns which are activated but it will not load any AddOns that were placed in the Interface/AddOns folder since you started the World of Warcraft client.