It's a phase that some kids go through at this age. You could try bumping her bed time back half an hour or waking her up half an hour earlier from her late nap. Plus you could switch to the Bed Time bath products with soothing chamomille and lavendar.
We would keep our boys that extra half an hour then instead of just sitting there for however long it takes to rock them to sleep we would read. Most of the time they would be out after 20 minutes.
This is the time you need to start reading at least 20 minutes every night. If you want to make it all about going to bed, then there are some fantastic books out there. Plus you don't have to be in the rocking chair. Sometimes my hubby and the youngest one are sprawled out on the rug. I've seen both of the younger boys fall asleep that way.
The main thing is to make sure there isn't any extra noise keying her up. Like if your husband likes to play video games in the next room with the sound turned all the way up then she's not going to relax.
Also it is important that she learn to soothe herself so you may have to sit in her room each night until she finally sleeps. Sit where she can see you but only half your face and cannot reach you. Be still and quiet avoiding eye contact and responding to her screams. Each night you move a little farther away until you're sitting out in the hall way then you either shut her door a little more each night or progress down the hallway.
Take care and rest well soon