if you mean this saturday the 10th... no, there's no training you can do.
if you mean next saturday the 17th, yeah, you can do a couple of things. First off, get out this weekend for 30 miles on Saturday. Ride again on Sunday, but just roll around for a while if you're wiped out from the 30 miler. During the week, try to get another ride or two in of at least an hour - go a bit faster, do some higher speed efforts.
You can do this ride no problem, it's simply a matter of pacing yourself. Take 2 water bottles, have a banana or 2 in your jersey pocket, have a good meal about an hour or two before you start - like a big bowl of oatmeal for example. Drink a water bottle at about one per hour, taking frequent drinks. Start eating after your first hour on the bike; a bite every few minutes as you pedal.
After 2 hours, stop, get off, maybe hit a c-store, drink an OJ or V8 (I don't like Gatorade but if you must...). buy another couple of banana's or maybe a fig newton or a powerbar. Refill your bottles.
Just roll easy the entire time. No need to set any records; even little efforts and small hills will start to add up on you.
You'll be fine.
Oh yeah, make sure the bike is mechanically sound and tuned, and that you don't have any fit / soreness issues.