By default a DHCPDISCOVER is broadcast and therefore seen by any DHCP relay agent in the path and therefore they can act on the DHCP 82 option. However, DHCPRENEW are unicast to the DHCP server and not seen by the relay agent (AP or switch). To accomplish this, the DHCP server would have to be configured to support DHCP option 54. However DHCP option 82 is typically trusted from the initial DHCPDISCOVER so there is no need for the relay agents to see the DHCPRENEW. Can you elaborate on your ultimate goal?