DHCP Option 82 in Client DHCP Unicasts When Lease Time is Over

[pamuditha_abeys]

I am using Linux DHCP server to issue Client IPs. Client IPs should be issued based on DHCP option parameters. So in DHCP request (Broadcast) it will have option 82 parameters. 
My question is after lease time when client want to extend the lease? How will it work? As I understood this will be a unicast packet and how AP can embed option 82 parameters into this packet. ? 

Thanks