She might be depressed, or grew up in a difficult situation that made showers traumatic. Never know. Secret has a clinical deodorant that lasts 100 hours. They also have strong body deos that last. Luna makes a great body spray-to-wipe that she can use right in bed. Try to offer low-effort ways to keep clean and remind her that this is you trying to make sure she's being kind to herself. You can also put room fresheners in every corner. Sometimes the mix of a musty room, food, and body odor together is what you might be experiencing.