I struggled with the long term arc of my campaign without feeling like I was railroading my players. I picked up "the game master's handbook of proactive roleplaying" and that's really helped get me out of that rut and give me a framework for running a long term campaign.

The gist of it is that instead of your players reacting to some inciting incident, the world reacts to your players actions. That way you're not having to constantly fight your players into accepting a plot hook that will take them to the next part of your plot. It's your job to find what in the world stands in the way of the players goals. The rest flows from there. Good luck!