There was a post the other day which I cant find anymore, but basically the Guy suggested that if new maps take longer than expected, making new game modes for already existing ones might be a good way to keep things fresh.
Like a "real" siege attack on Feitoria, or an attack from water. Creates a whole new gameplay experience for arguably less invested time.
We're actually looking to make more variants like we have for grad, etc. They aren't super-fresh content, but they're still content and anything could help at this point. Annoyingly, things aren't as simple as they might seem, but we've definitely been focusing on hiring more level designers and game design folks to speed things up.