Are you exchanging the paper ticket because of the flight itinerary changes? Few months ago, I had booked *A award paper ticket with LO. I had a change of my travel plan. I called back, they cancelled my old itinerary and changed to my new one because they had not actually "printed" the paper award ticket.

I think you can do it ONLY if they have not printed or issued the paper tickets. Otherwise, you have to mail your paper ticket back or bring it to the ticket office for re-issue.