Do I need to re-register for my soft power visa course every six months in Thailand?

I did soft power/Thai cooking and completed the course but I schedule a class every time I come back. I find it fun and you get to meet people. Seems worth it to me in case things ever do change.

I also love Thai food so I legit wanna keep learning.

Legally there is no requirement AT THE MOMENT to continue any soft power activities beyond what you had in your visa application.

Beware that could be changed by immigration at any time, however they will announce that change

Currently it’s unlikely that immigration is going to question whether or not you’re still engaged in a soft power activity.

That being said, you would no longer be fulfilling the conditions of your visa and the immigration officer has the power to deny you entry or to only stamp you in under the visa exemption scheme (if eligible).

If immigration ever wanted to crack down on the DTV, the easiest ways to do so would be to demand recent proof of status (remote work or soft power course) and/or financial proof of 500k THB.

Up to you. You'll be stamped back in if you do or don't.