Tools | Reports | Properties.
Configure the options to show Map IDs. You can see which topics do and do not have map ids.
The Auto Mapid function is designed to be used when every topic requires a mapid. If you have some topics you want to assign mapids to it is best to do this manually. You can still use the Auto Mapid function but you will find duplicate mapids for any topics that were previously mapped. You could always just delete these after you have mapped. They are easy to spot as there is a numeric identifier on the end (e.g. the original mapid would be "NEW_TOPIC" and the duplicate "NEW_TOPIC1").
If you decide to go down the manual route, you can use the Topic Properties report to see which topics have a no mapid assigned to them. I'd use the reports options to limit to report just on folder, status and mapid to minimise the report's clutter.
I am also using context sensitive help but I cannot find the report mentioned in this post to find which IDs are new and are not mapped (from a previous set-up).
Under TOOLS, REPORTS - I don't see "properties". I am using RH8.02.208
Also, once I see which properties need to be mapped based on my update and based on those shown in the report with no IDs, how do I do that?