I've found that when the Client Information doesn't get updated properly, it's because either the Admin process didn't run against the request, or that the Admin process believes that someone else modified the person document, and it marks the request as failed. Probably when the Client's Password information is updated.
Open your Admin4 database, go to the Requests -> All Requests by Action view, and scroll down to 'Update Client Information in Person Record'. Open each twistie to verify whether the request was processed or failed.
If failed, you can mark the request to be processed again.
That has usually fixed THAT particular issue for me - almost 100% of the time. The only caveat is, you need to make the check a couple times a week, otherwise requests will fall off.
I've never found a way to force the Client to resend the information, possibly short of re-upgrading the client. I would suspect one could write an agent to submit the AdminP request, but have never looked into it.
My other problem has been with the usefulness of the information over the years. I've got clients (well, HAD clients) that had over 10 entries of mixed machine names, Notes versions and dates. Finally created a manual agent to wipe the info completely, then, when i think about it, I can wipe the fields and reprocess the AdminP request, which leaves me a clean, one line log of the user's configuration.