How to refresh a list box.

Hi, I am currently writing a script that lets an administrator approve/disapprove messages. The script retrives all message with a certain byte set to 0 and builds a list box from where the administrator can choose a message to be viewed and disapproved/approved. Once disapproved/approved the byte is set to a corresponding value. Now I would like to refresh the list box, so the just approved/disapproved message does not show up any more. Just re-fetching info from the server does not seem to work. Any help? Michael