**** Change server ip ****
Boot the server with the new server ip. (the new one you want to use)
DirectAdmin will not be running, as the license file will be invalid.
Contact DirectAdmin to obtain a new license file. They will change the ip in the license.
Get the new license file:
   
   cd /usr/local/directadmin/scripts
   ./getLicense.sh UID LID

Where UID and LID are your client ID and your license id.
Ensure the license downloaded properly by making sure the file contains no error messages.
Start DirectAdmin with the new license:

   service directadmin restart

(The taskq may have already started it, thus the restart instead of just "start")

Download the ipswap.sh script from directadmin:

   wget http://www.directadmin.com/ipswap.sh
   chmod 755 ipswap.sh
   
Execute that script with the old and and the new ip.  Example:

   ./ipswap.sh 1.2.3.4 4.3.2.1

where 1.2.3.4 is your old ip and 4.3.2.1 is the new ip.
This script can be run on any ip, so if you want to change all ips with new ones, just run this script for each old ip with the new ip.  Just ensure that you match the new server ip with the old one.

Restart everything:

   service httpd restart
   service proftpd restart
   service exim restart
   service vm-pop3d restart
   ...

Make sure they are correctly binding to the new ports by testing them.

You'll need to update the users list cache so that you see the new results in the show users lists:

echo "action=cache&value=showallusers" >> /usr/local/directadmin/data/task.queue