Don't you have to re-certify them each time a new list is updated?
Not if your OFAC software is halfway decent. After you clear a false positive to a particular name on the list, the software should "tag" that customer to that particular entry as a "clear." The only time you would have to recertify is if a new name was added to the list that has similar characteristics.
I first started using Bridger wa-a-y back in 1996. This particular annoyance was one of my constant complaints and about a year later, they came out with a solution. I think most OFAC software database filters now have that feature.