No statute of limitations or similar statute or the doctrine of laches shall bar the right of recovery for fees and expenses under this chapter, but this section does not apply to claims that may be otherwise barred by law prior to July 1, 1961. It is not necessary to bill currently any person for those accounts determined to be inactive, or currently uncollectible, or for which it has been determined as provided by law that there is no present ability to pay. Current billings must be made for amounts chargeable by law or for which it has been determined the patient or responsible relative presently has an ability to pay, but the manner of billing shall in no way affect the total amount due.