Writing gets done somewhere other than at your keyboard. Waiting for the kids to finish soccer practice, unloading the dishwasher, in line at Costco are all places where you make up what you want to write up. All you need to do is pick the place and time in your novel you have not yet written and focus on it. See the characters, understand their needs in the moment, place them somewhere to interact. Then hear their words. What words? Characters say and do what they think will get them what they want in the moment. If you know what they want you'll know what they will say. If their goals are not easily compatible with their situation you will have dramatic tension. If you have dramatic tension you will hold the reader to the scene to find out how it ends. The key to all this is directing your idle brain time to the task of visiting your story.