I think any plot needs constant revision.
It's a really bad idea to fixate on too much when writing. What you thought was a good scene, or plot line, a few weeks ago isn't necessarily the best you can do.
A lot of the time when I write, I have an arc that I need to happen, or maybe just want to, but it makes little sense, so I'll tie another plot in from elsewhere. Makes the whole thing more dynamic.
It's also easy to only focus on one or two characters, so try to make minor characters have their own arcs as well.
Also, if there's anything about your setting that is different to real life, have you explored the ramifications of those changes?
Warning! this post may contain sarcasm, please re-read it in a funny voice
The old spoiler was out of control, it had to be stopped.