How do I motivate Alzheimer's patient to not stay in her chair most of day?

At this point you are down to what makes her happiest I would think?

Really, she has probably forgotten how to do things. My Mom was an avid reader and lost the ability to read and comprehend a book. She never played games or did puzzles. No teaching them because short term won't allow them to retain the info.

If they enjoy watching TV then let them. Maybe get her out of the house for a ride or a walk.

If you want them to be more productive, maybe encourage them to go to activity center.

If they prefer to just sit and watch TV, just let them be.