Sometimes the only way to liven your prose is to hit the delete key hard and often.
The first step is to highlight all of your PET phrases and paragraphs. You know which ones. The ones that made you pause and thing, "Wow, what a great writer I am. You may need to delete them. Not because they are not good, but because they are often beautifully written author intrusion.
How many characters do you have? How many do you need? How many wonderful scenes can you give to a single character to eliminate two or three "walk-ons"? Too many characters, no matter how fascinating and well-defined, can bog down your story. Save some of them for another book. You do plan to write more, don't you?
Although an excellent tool for description and dialog, adverbs in exposition are the death of active fiction. Shakespeare might have said, "Out damned adverb," before rewriting it to "Out damned spot." Before I cut over 40,000 words from my book in progress, I used the following sentences. #1 In the kitchen, Melissa giggled softly. Revised, it reads - Melissa giggled. #2 "Daylight then," Kathin conceded firmly. "You can finish it after your morning chores are done. Now, get upstairs." I think it is obvious from the dialog that she was being firm. Or, at least I thought so after I forced myself to delete over 4000 adverbs from the manuscript.
Deleting hurts. I know. Deleting words and sentences you've slaved over is excruciating, but if I can do it so can you. Whether I ended up with better novels will be decided by you, the reading public. Meanwhile, I have concise drafts that interest the dickens out of me.