How can you get rid of pain from chronic re-innervation from l5?

Depends. The treatment of neuropathic pain can vary from medicinal, such as gabapentin, to surgical treatments, including removal of the anatomic lesion causing the pain. If the pain does not respond with such treatments, then other modalities, such as spinal cord dorsal column stimulation may help.
Near-infrared heat. Low-level laser therapy (the application of visible red or near-infrared light) relieves inflammation, speeds healing, and reduces pain. Amazon.Com has a $169 near-infrared heat lamp that they sell -- it gets rave reviews. Quite frankly, i love mine! it is quite effective for back pain. Also acupuncture can sometimes be helpful -- as can chiropractic work on your back. Good luck!