You have to be a bit consistent. Increase by 10-15 minutes and hold for a few days. Then increase a little more. Basically, give her body some time to adjust. She is used to going to sleep at certain times and so expects it then. Try not to let her nap inbetween. As I said, walk around, do songs/ rhymes..very low key stuff so as to not tire her too much. After a short nap, you can decrease A time by 15-20 minutes. I feel that you will have to experiment a bit with A times to find what suits her since she seems to have high sleep needs