Question about how to fill out a conditional waiver

I have a question about conditional waivers. A lot of general contractors don't pay invoices within 30 days and at the time of submitting a new invoice (which requires the inclusion of a new conditional/unconditional lien waiver), more than the current month's billing is still outstanding. If this is the case, should the total amount outstanding be put on the conditional waiver, with the through date of the current billing period, rather than just the amount of the current billing? Or are the prior billed & unpaid amounts covered by the conditional waivers that were included with those billings? It just feels wrong to put only the amount of the current billing on the conditional waiver with a through date of the current billing, if the previous billings are still outstanding. I hope I was able to explain clearly what I'm asking.