When you convert an IAP, in the flash of the AP, the "master" or controller IP is set. You can make this dynamic by:
(1) provisioning access points before the controller was reset so that the AP uses ADP or DNS to find the controller
(2) Using a console cable and change the setenv master variable to nothing.
last resort:
(3) Using the reset button on the AP to turn the AP back into an IAP. You would then have to convert it again by pointing to the new ip address.