Invoicing On-going Customers - A New Invoice Each Year?

[Terry Morse]

I am helping a friend keep the books for her childcare service using GNUCash, but have no training in accounting so I need some advice.

I am using an invoice for each customer to track their charges and payments. As we are about to enter a new year, I need to know whether it makes more sense from an accounting standpoint to create a new invoice for on-going customers each year, or should I just keep updating their original invoice as long as they remain customers?

Is there a more sensible or efficient way to keep track of accounts receivable for the business than by invoicing? We don't actually send the customers invoices, as they make their payments (usually) in advance at the start of each week.

Thank you,
Terry