Jive has a Terms & Conditions plugin that I think would accomplish your objective. Upon a member's first visit, they must acknowledge that they agree to the terms of the community. If they do not, they cannot create a profile. The acknowledgement is captured and stored so you can lookup when they've accepted within the Admin Console. The reset sounds like a customization. You could perform this manually by making edits to the T&C document. This would prompt everyone to re-accept the policy.
I think this is also part of the core product in 4.5.
To force the re-acnowledgement, you could manually force everyone to re-agree every few months. We needed to re-validate email addresses every few months which is a similar concept, so we worked with Syncapse, one of Jive's services partners, to develop a solution. Basically, each account has an "expiration" date. As the expiration date nears users receive an email with a link; they have to click the link to revalidate their account. You could probably do something similar for re-agreeing to the Terms.
Dan and Suzanne --
Hi Bill, be sure to contact your Jive sales representative for details on that plugin, if you decide to go that route. Thanks, Dan and Suzanne!