Have you had a recent MRI? A grade one spondylolisthesis is actually pretty good - it's when it advances further that surgery is often needed. I had surgery when it reached a grade 3 level and am glad I did. I don't know of any treatment that can reverse the slippage due to spondylolisthesis.
Rt thumb fusion '13. R&L thumb arthroplasty '12 ; RT TKR & Bilat CTS' 11. Fusions: L5-S1('87), L4-S1('93), C5-C7('06), L3-S1('10), C4-C5('13). C5-C7 foraminotomy '08