Hiya
Think your post is on the wrong board hence the lack of replies! I would say if naps have been shortening then yes she probably does need an A time increase. Given what happened yesterday I would say that just proves it!!!
Just try adding 15mins A time for 3-5 days & see if that helps to increase her nap. If no real increase, then add another 15mins. Doing it gradually like this will avoid her becoming OT. Or you could see how she fares overnight tonight & then if you get a good wakeup tomorrow repeat the same!
HTH.x