Incident due date re-calculation when status changed to closed

Hi Experts,

I am using SAP solution manager 7.1 SP13, I have configured incident management with SLA determination and escalation.

SLA clock stops at proposed solution status and the due by is getting re-calculated when customer accept/ reject the solution.

my requirement: Due by date should be re-calculated only when the customer reject the solution. If the customer accept the solution due by date should not re-calculate.

I have assigned the duration SRV_RR_DURA at proposed solution status. Please advice.

Thanks

Kumar