Policy review does not sound like much fun. This is why you would do it in small pieces. It is also why you have been putting it off!
Best practices suggest that you review a third of your policies each year, probably in the order the policies appear in your governance manual. Every time a policy is reviewed, that fact would be noted in the governance manual. If any changes are made, those changes are dated. In this way your organization will always know which set of policies were in effect at any particular time, should it become an issue.
You can also review a policy out of order – whenever you are thinking that a policy needs an update.
Some groups put policy review on the agenda each meeting – so that it actually happens. You might have trouble convincing people to come to a meeting that had nothing else on the agenda but policy review. If you sneak one in each meeting it will be nearly painless.