Assuming you have a bit of extra time, there is a method to retain your DO IP address.
Spin up a new DO Droplet for a few hours and migrate your MIAB to it. Update your DNS to point (temporarily) to that new Droplet. Set reverse DNS. Ensure everything is working properly.
Reimage your old Droplet and install the current MIAB version. Migrate from your temporary Droplet to your original Droplet. Set reverse DNS. Update your DNS again.
Destroy the temporary Droplet. DO charges by the hour, so there should be only minimal expense.