The thing that does jj2 boring is maybe that evryone hostes battle1, battle2, and battle3. They aren't that fun.
Host more custom levels featuring on better tilesets would make it more fun playing in a server, host different gamemodes than battle and CTF all the time.
Be more active, use jazztool to check if there's something wroth up on the server list.

The game isen't that alive, like in school time, there's no servers becuse the game is mostly spread in Netherlands.
Host on TSF. Most people has TSF.
There's more servers on TSF than 1.23, so why keep hosting there?
Also, evryone is making levels and tilesets, for get high rating on jazz2online.
Why don't you just download some other stuff and host that?
We have enoph levels on jazz2online for 30 years again before they get boring.
It's waster of time making more multiplayer levels in JCS.