I found this information here as of 2019-06-21.

Question:

I installed TS3 on my VPS and used my one-time-use token and have since reinstalled windows on my PC.
Without reinstalling TS3, how can I generate a new admin token? I have SSH root access to my TS3 server.

Answer:

You must use the query command (with the serveradmin query account) :

login serveradmin <password>
use <server ID> ("or" use port=<virtual server port>)
tokenadd tokentype=0 tokenid1=6 tokenid2=0