I would like to offer that we have a server wipe every 3 months. Wait, wait, hear me out....
One of the things that makes the game fun is base building. We all like to see them go up and experiment with different locations in the game. Having a wipe means that you get to experiment with different places and the joy of making something new.
The other thing is that wipes mean is that tribes to not get too big. You may have a dominant tribe for a few weeks, but with the knowledge that everything is going back to square one, everyone knows that it wont last.
I also submit that before the wipe there be some prizes for things like highest level dino, vote on coolest base, that kind of thing.
Oh also have a few prizes for first, like first to hit level cap, first to tame a Rex, Spino, etc, first to summon a boss monster, etc.