Harrison and Mecklenberg, Inc (They should be in the white pages)
Have really made a name for themselves out here assisting mineral owners like yourself get the old tired leases released. I’m not up to speed on your exact situation, but I’m sure if you gave them a call they will tell you pretty quickly if they can help or not. They do charge a premium in my opinion, but if the new well lasts another 30 years, then it was well worth the fee they take from the bonus money to get moved from 1/8th to 3/16ths (roughly 33% more revenue from 1/8th (12.5%) to 3/16ths (18.75%).
Most of the vertical well operators in the area have lost a lot of old legacy leasehold recently due to Harrison & Mecklenberg and might offer a settlement to amend your royalty if they won’t release the lease.
Squeaky wheel always gets greased.