How to surrender dutydraw back online

we had export the goods to Sri Lanka with T&C CIF and documents against payment. We have been remitted the full payment by buyer. As inform by buyer that he has not received one package of material and same has been claimed by us from insurance company and received the claim amount Now in order to make the payment of claim amount to buyer we have to surrender export incentive . So let me know how to surrender the Duty drawback