[Mashiro]

I had to do the same for my domain for renewal. I had to type in the stuff I typed in first time when I issued the certificate. I suggest using a cron to run it every 3 month or something. I set it up and now have to wait for the result in 3 months of time.

I would like to see your cronjob solution.

The issue I see at hand is that probably a cronjob can't update the DNS challenge records for you, unless your DNS hosting provider has a API for that and you write a script that somehow manages to update it properly (how do you control issue with the waiting time of DNS propagation updates???).

Automated DNS challenge does exist but as far as I figured out during research it only supports GoDaddy DNS so far.