How can we improve WHMCS?

Currently if we offer a promo code to a client which runs for say 12 months, and the client wishes to renew the service, We must re-issue a new coupon code and the client must re-sign up to activate the new coupon. its a hassle and an inconvenience to the client to go through the whole process again.
It would be a much simpler process for us just to be able to extend the coupon code period from say 12 month to 24 months etc..