A deleted domain doesn't remove all related configs?

Like SSL Certificate and Server vhost config?

I just deleted a domain, and added it back and it still use the old certificate.
I doubt auto renew will work as no well_known file on public_html folder now.

Child-domain has their own sub-directories, and they are always soft-deleted.

Their configurations are removed from the server but their data is not deleted as it could belong to master domain. So .well-known should be there in doc root of child-domain and not the master domain.

In case you choose to recreate this child-domain using another sub-directory then Let’s Encrypt can issue new SSL again.

SSL certificates are also kept.

Not child domain or subdomain.
It’s root domain I just deleted.
and added back then re-issue SSL and it uses old certificate.

Not child domain or subdomain. It's root domain I just deleted. and added back then re-issue SSL and it uses old certificate.

The previous SSL are kept as they are saved in a separate directory

/usr/local/lsws/conf/vhosts/SSL-example.com