Hi,
It seems losing the date and time whenever batteries are changed is a quite common problem of Axims. The problem is discussed on
this thread for example. The problem can be solved by changing the backup capacitor as it's discussed there.
For those looking for a "less agressive" solution, I've developed a small app that I believe it could be useful (at least, it is for me). It works as follows:
Once installed, it places a battery icon in the system tray. Whenever you want to replace batteries, tap on this new icon. You'll be asked whether you want to replace the battery. If you answer yes, the app stores current date into the flash and suspends the Axim. Once suspended, just replace the battery and power on the axim again (powering on just after replacing is important because if you don't do so, the stored date is no longer correct). During boot, the app will detect correction is needed and will update the incorrect date with the stored one adding 60 seconds (more or less the time it takes replacing the battery and booting).
Let me know if you find it useful.