What are your battery habits? Do you tend to drain the device's battery all the way before recharging it again? If you do, then that's the worst thing you could do for the Li-Ion batteries that a PocketPC uses and it's the fastest way to ruin it's battery. I'm sure that if you've been doing that for 6 months then it would be near death.
I don't know of any way to fix a battery, unless there's just some software or hardware that's running it down, or showing a false value (perhaps the first virus?). What I'd do to determine where the problem really is is turn off all battery warnings and things that turn off the device if the battery is however low. Then just play around with it until the device just shuts down without enough power to keep running. If it's really only 1/16th charged then that shouldn't be more than 10-20 minutes of run time.
The only thing I can think of is to buy a new battery before Sunday just to be on the safe side. I don't know where you can get an @migo battery other than ordering it from urthere and having it shipped.
). Good luck, but it's always good to have a second spare battery anyway.