1. Look for places where you’ve summarized a scene. Dramatize it instead.
2. Look for scenes where a character has a lot of interior monologue. Bring in a second character for them to talk with.
3. Look for time gaps. What happens in them that you could make into a scene?
4. Add another character. Perhaps someone your main character doesn’t want to see, or wasn’t expecting to see.
5. Add a subplot. Are there any existing characters you could give scenes? Maybe your villain?