You can completely override how the price and validity display using the "Price display of plan (default: [AUTOMATIC])" parameter under the Presentation tab. It's also possible to override that to an extend using language strings. I believe that should be using the following.
Key: X_CALENDAR_YEARS
String: one calendar year|[X] calendar years
The first half controls single calendar year which you could change to the following.
Key: X_CALENDAR_YEARS
String: this calendar year|[X] calendar years
You can override language strings directly in CB using our built in language override feature shown below. It has a searching feature as well to help find language strings to override.
www.joomlapolis.com/blog/kyle/18701-language-overrides-have-arrived