Ah, this web site, which I thought was the only place where you could register, says it is based in New York, so they can’t register new ones, which web site did you use to register it?
One Russian research organization, ripn.su, is responsible for registering domains in the .su
zone. They in turn assign registrars, here is a complete list: https://ripn.su/domen-su/spisok-registratorov/ (use Google Translate). I registered with beget.com.
Although I think they will refuse you if you can’t prove your identity. Documents issued in Europe, USA, UK and so on are not suitable for proof of identity.
PS: $29.95 per year is very expensive, Russian registrars charge $4-6 per year.
Monitor is now at www.lenp.su/monitor/. I changed the domain, but forgot to configure redirect from the old domain monitor.lcomrade.su. Now everything should work properly.