If you're commuting 12 miles each way daily, a century shouldn't be out of the question. If it's only 6.5 miles each way, well, it might be a bit tougher but it's still doable.
If it was me, I'd do progressively longer weekend rides between now and "century day" - say something like this 30, 40, 50, 65 and then the weekend prior to the event, do 40 again. On my daily commutes home, I'd up the intensity a bit on Tuesday and Thursday. Friday and on the weekend ride, I'd be shooting for 60% of max heart rate for the majority of the rides with minimal stopping.
There isn't a need to ride farther than 70 miles prior to event day. On event day, ride to finish, not to finish fastest.
Take one day a week off from riding at all - recover.
Added: Looking at the route profile, the hills come at the start. That's good and bad -- finish them and you "coast" home (okay, not literally). Otoh, they can wear you out if you don't pace yourself, leaving you with no energy or desire to finish. So, go ride parts of that section on the weekend. Get an idea of what pace you can set yourself without burning out. The more hills you can do beforehand, the more informed you will be about how you're doing on event day.
Last edited by 20_700c; 07-25-13 at 06:37 AM.