In theory, you could transfer your Value Bundle and its custom domain parsonsfabcreation.org to a new site every term, and let all the old archived sites simply keep their default free WordPress.com addresses. You'd need to put in a request for staff to do this for you, so it would be something you'd need to think about every term.
When you create each new site, you could give it a name that you'll ultimately use as its archived name, for example: pfcfall2012.wordpress.com, pfcspring2013.wordpress.com.