I'd recommend harnessing the motivation that brought you here. Whether that means re-reading old stories, bouncing ideas off your friends, delving into other things that make you nostalgic (I sure do,) or just thinking back. I'd also recommend reading other games to get ideas for things you can do that you might not have thought of before.
If I need to feel energized, I usually pick a bunch of songs to suit my mood. I wrote a lot of pages on my game by listening to YouTube playlists. xD I tend to listen to really upbeat stuff while writing horrible tragedy because ... contrast is fun and I don't get burnout, I guess. But I've also listened to dark stuff to set a mood, too. Alternatively, take a break and do something mindless. If you let your thoughts wander, you tend to get inspired. Take a shower, go for a jog, tidy up a room, play a simplistic game, wash some dishes, I've had great ideas from all of the above.