I'd say use the current players, I am fairly sure that the bigger part got here with people they know. I haven't been at fg too many times but when I was here it was because my friends asked me to get online and play with them.
Not too sure how the Recruit a friend system works here or even if it is here, but play around with that. Make it known in game and at the forum that if players would like to see the server grow again that they are the key to the solution and shouldn't blame staff members for everything that they can do them selves
! FG is a stable server comparing it to others, I was staff for a great amount of time at another server which has a terrible client (this should spoil the server but its not meant to be an advertisement ) but we maintained a 100 person playerbase only by staying in touch with friends, now that the old staff team I was part of got cleaned by the owner and co owner it resulted in player loss down to 15. So I'd say use connections the people have and reward them for doing so!