Can I withdraw in round 3 without paying add.fees?

I got ANDC in round2 and got upgraded to Ramlal Anand in round 3. I had paid already 20k in round2 to accept the seat and this seat got automatically accepted so I have to pay 15k to secure admission. But I want to withdraw my admission and get my refund back? Do I have to make the payment to withdraw later on? If I am not making the payment the seat get cancelled by itself but what about the refund?