Questions always lead to more questions. kevint is hinting at the correct process.
I think you are asking about re-hardening the blade. If that's the case, you'll need at least 800C or 1500 F for a carbon steel and probably higher for stainless.
Re-hardening the blade can be done, but not in home build shop equipment and even then, with a finished-down-to-sharp-razor-blade there is a strong possibility of creating a newly hardened blade with a wavy potato chip edge.
I still need to know more about this blade. Where in MN? Send me a PM please.