|Hello, you don't mention how old your daughter is, but I know by the time my son started sleeping through the night (at about a year old), I found his overnight diaper really reeked in the morning! At that point, simply tossing it in the diaper pail and washing like the other diapers wouldn't do the trick, they would keep a faint smell even after a wash, so I started either rinsing the morning diaper (like I would do a poopy diaper) or simply throwing it in a small pail and covering it with water (like a mini wet pail for the overnight diaper only).
That did the trick and I never had lingering smell issues, so I figured it probably wasn't anything to do with the diaper or build-up, just that the pee was much more concentrated and plentiful overnight and the normal routine didn't cut it anymore for those. So you could try doing something like that, but if you do and they still smell after a wash, or if the other diapers (not overnight) start smelling like ammonia, then I would definitely strip them.
Hope that helps!