"Although you might find yourself becoming irritated and impatient if someone with dementia repeats the same phrase over and over, try to take a deep breath and remind yourself that he's stuck and doesn't know how to move on from where he is. It may help you to visualize the situation as if the person with dementia is in a car that's stuck on ice. He is probably spinning the wheels of his mind, yet unable to get any traction to be able to move forward.
Remember, too, that arguing with someone with dementia, or pointing out the fact that he's perseverating, is unlikely to help. You can try to use distraction to lead him away from the word or action that he's stuck on by offering him meaningful activities or music of his choice."
https://www.verywellhealth.com/perseveration-98602#:~:text=Perseveration%20is%20a%20common%20symptom,word%2C%20phrase%2C%20or%20gesture.