Cs executive

Hi friends, can exemption be availed in CS exam... In previous Dec 2014 exam I got exemption in one subject.. I didn't appear for June 2015 exam.. Can I avail that exemption in Dec 2015 exam..? in case yes then should I need to apply for anything to avail it..? one more question.. If in case I get this exemption.. but I would like to surrender this exemption is that possible..? Suggest you valuable information. ..