There are many reasons for doing a review annually. Here are some.
Are you doing business through a new joint venture with another company? If so, it's a good bet that you are sharing information in a manner different than before.
Has your marketing department changed its approach to the renting of mailing lists? Perhaps a standing decision not to rent lists has been reversed or some other new use of customer information has been instituted.
Are your Web links, e-mail addresses, telephone numbers and street addresses still the same? These little things can be overlooked. If your policy included the name of your privacy officer (which is not always a good idea), has that person changed? Maybe your company created a privacy officer position that might be described in the policy.
Are you collecting more data from your customers? If not, maybe you are buying more data about them from third parties.
Is routine maintenance a good idea? I drove my last two cars for 13 years and 12 years, and both were still running strong when I finally decided to get rid of them. I found that paying attention to the basics can be worthwhile.