As far as the original time period, this seems to be a problem in some jurisdictions.
If you already have the initial background check done, all the really need to do is contact your references that you submit. Especially if it's within the same year that the original invest was completed.
As far as the renewal, provision is made within the statute; they have to but only one time for an additional 90 days. NJS 2C:58-3 (6) f.
I don't know why it seems so hard for some to get it right.