Are there any treatments for aortic stenosis other than surgery or percutaneous aortic valve replacement?

Surgery. This is a mechanical obstruction to the outflow tract of the left ventricle. Removal of the mechanical obstruction with a suitable replacement is the standard of care proven to prolong and preserve quality of life given suitable candidate. Prosthetic choice depends on age and pathology. Percutaneous aortic valve interventions other than straight baloon valvuloplasty reserved for inoperable candidates.
Long term, no. For "critical aortic stenosis" (valve area less than. 7cm2) surgery, and occasionally valvuloplasty is the only curative treatment. Prior to the critical phase of aortic stenosis, the condition is temporized with medications that support overall heart function.