Send a reminder email a few days BEFORE sending a new invoice.
This should be pretty self-explanatory. Just an email that reminds you that you will have a payment due on a certain date. It doesn't even have to be an exact date. It could just be "in 7 days" or whatever.
More specifically send the reminder a few days before taking the money from my bank. I didn't even get an email when the Invoice was created and debited the same day.