In my current WIP, I re-read through some of my chapters, and they seem completely dry and dull. I need to add some oomph to it- it seems my descriptions, and just plain storytelling (in some of my chapters) are mundane. What should I do to give it some excitement to keep the readers engaged?
One possibility is perhaps you weren't particularly engaged while writing this. Maybe it was a scene you just slogged through because you needed it. If you aren't personally interested, it's difficult --not impossible, but difficult --to make it interesting for the reader. Here's some good advice from author Rachel Aaron:
Every day, while I was writing out my little description of what I was going to write for the knowledge component of the triangle, I would play the scene through in my mind and try to get excited about it. I'd look for all the cool little hooks, the parts that interested me most, and focus on those since they were obviously what made the scene cool. If I couldn't find anything to get excited over, then I would change the scene, or get rid of it entirely. [emphasis added]
Conversely, if you are excited by a part of the story --or were, when you wrote it --but it still reads poorly, then not enough of what makes this interesting is making it onto the page. You might need to flesh out your back story, make your descriptions more vivid or more full, or put more of the character and narrator's attitudes and outlooks into the writing. I used to think problems like this were plot or dialogue issues, but they're more likely to be issues of immersion --you haven't done the work to put your reader inside your settings, and inside your characters' hearts and minds.
Finally, sometimes a section just needs to be cut entirely. To quote Aaron again,
I decided then and there that, no matter how useful a scene might be for my plot, boring scenes had no place in my novels.
Many books would be greatly improved with some ruthless editing.
Put conflict in every scene. A protagonist and antagonist in every scene. A goal in every scene, and something that stands in the way of the goal.
To increase tension ('life') present the protagonist and antagonist as equally opposed with opposing forces. The protagonist wants to make it to the fae castle; the antagonist wants to keep the protagonist as a slave. The protagonist wants to summit Everest, the antagonist (nature) is a formidable opponent.
A goal in every scene, an antagonist in every scene. Kill the scenes that you don't need. Review the scene-sequel model of storytelling.
You may want to make sure you are adding plenty of conflict throughout your chapters. If your writing seems dull or boring, this might perk it up. Give your characters some resistance or challenges to overcome. It doesn't have to be earth shattering. Some fiesty dialogue or uncomfortable decision making might be enough, depending on where you are with your story.
Also remember most scenes should have their own arc, with rising and falling action, climax and resolution. (though on a much smaller scale than your main story arc or subplot arcs). While scenes don't necessarily equal chapters, they should overlap with your chapters in a way that each chapter gets a bit of the exciting stuff.
And, like @ChrisSunami mentioned, sometimes you just can't make it work and have to get rid of it. It can be devastating to undo something you've worked for hours or days on, but it only hurts for a minute. After I've dumped something I couldn't force into the story, the rest begins to flow so much better.