How long are you leaving in between naps? Could be that she is over tired? Sounds crazy, but the longest my DS could stay awake during the day at that age was 2 hours. In the mornings, he was a grumpy nightmare and it was often more like just 90 mins.
So our routine would be a bit like this: he wakes up at 6.30, has milk, 40 mins later has a bit of breakfast, a bit of a play, nappy change if he poos, and then back down in his cot for a nap at 8am! He would then sleep for about 40 mins.
The we would go out for the morning, baby group (milk feed whilst out), shops etc, and then he would have another little 40 min cat nap at around 1030, maybe 11am if i dragged him out. Usually had this one in the buggy. Then home for a bit of lunch, and then back to sleep at around 1pm, and then another little nap at around 4pm. I usually found he could stay awake longer in the afternoon (sometimes almost 2.5 hours) but in the mornings he was dreadful!
It always seemed really daft to me putting him down for a nap at 8am, but it was actually quite useful as I could get dressed, put face on, eat breakfast etc ready for the day when he woke up! It might fuckup your lovely long post-lunch nap, and she might end up having more short naps during the day, but IMO getting them to sleep when they're overtired is just a total mare. Might be worth a try? Also, do a mini version of your bedtime routine? Story in dark bedroom and then into sleeping bag etc?We do this every time still for daytime naps and he is 10mo.