Who is the manufacturer of your current tackle binder. The companies that make the inserts are not always the same company that make the binders. It is possible to find out who made the inserts and contact them directly to see if they are still in production for another company.
In many cases, and for the cost, sometimes it is easier to get a new binder.
Let me know and I'll do some research for you.
TackleMan
http://www.tacklemanufacturers.com