Apple - Is there any way to have an iPad auto update its date and time?

It should update automatically by default (Settings → General → Date & Time).

Are you running the latest iPad OS (3.2.2)? I have a vague recollection of a bug in the iPad that caused the time to go out of sync that might have been fixed in a software update. I can't seem to find any info about it, but you might want to update the software just in case.

It seems that the setting is only available on the 3G model.