Here's a few problems and their solutions that I have in mind.
1. Most original players don't even know that the server re-opened. (I personally stumbled across it and decided to jump back in.)
As people said before me, you could use the massive list of emails who registered and maybe more people will realize the server is back.
2. There are 40 illegal factions which is the avarage count of active players throughout the day time. (Most of them are not active)
You could limit people's ability to open a faction so they have no choice but to join an existing faction and boost their activity.
3. There's a huge barrier for new players who want to start roleplaying, the only way them to learn would be from an experienced player they know personally.
The answer to this is obvious- Guides.
4. Many players are just looking to provoke shootouts, there is no real consequencess to killing whether it's OOC or IC.
Increase jail time for DM and IC killing.