To get more renewals paid, you should be utilizing Account Updater. You should also have an expiry date guesser, as well as soliciting new expiry dates from those customers which you could not update through automated means.
In addition to that, you should have an automated retry strategy in place to retry the payment at the day and time it is most likely to be approved.
If you have any questions or need assistance with implementing Rebilly, please contact us. You can email us at firstname.lastname@example.org, chat with us or schedule a talk with a billing specialist below.