I definitely agree with the other posters about shooting for different distances or even adding in some cross training activities. And group runs can be totally fun. Most have a very different, and good, vibe than team based stuff.
I know it seems to be a bit cliche right now, but I'd also recommend looking at doing some trail races. You can train as much or as hard as you want for them, but they completely take away worrying about splits and PRs and stuff like that. The races have a super cool, welcoming atmosphere, too. If you did that for a year or two, you could possibly develop a lot of strength (and maybe that spark) to dive back into faster track and road stuff.
Oh, and a third thing, also perhaps a bit cliche and silly (at least on these boards), but I've been really enjoying playing around with Strava. There is some extra motivation there in tracking your runs and progress, and it also helped me hook up with two local group runs that I didn't know were going down.