Change in retention time

Let me first start off by saying that I'm new to NetWorker and I am still learning. Recently, management changed the required retention time from 1 year to 1 month of a particular backup and it belonged to my "1 year" pool of tapes. I also have a "1 month" pool that now will be used for my future backups. On the tapes in my 1 year pool, the saveset that changed took up about 75% of the tape and the rest was filled with other items. My goal is to free up as many tapes as possible with this new change, but the tapes still have other savesets that need to be retained for 1 year on them. Is there a good way to free up the space and consolidate the data on my "1 year" pool?