Hi there. My original account went inactive, but I'd like to give Subeta another go without needing to start all over. Is there a way to reclaim an inactive account?

if by inactive you mean frozen (crossed through the name), then you likely need to email the site about it, assuming you self-froze. I do believe the site can also freeze you if they are banning for an infringement of some sort. If you mean inactive just in that you haven't logged in in a long time, I don't know that there is anything more than logging in again (may need a name change if someone claimed your old name, although that appears to have been bugged and accounts haven't been clearing properly in years)

Depending how long its been you may need to email for direct help. They had users confirm emails and essentially "sign up" for the kumos side where the site is slowly shifting. If it's as stated above and it was frozen rather than time passing you may need help to get back in. I believe you can find the support email in the Contact US at the bottom of site pages.