Sometimes all you can do is let her cry it out. It's the hardest thing to do as a dad.
What worked for me was putting her to bed and sitting on her floor with my back to her so she knew I was there. I didn't talk to her while I sat there or when she got out of bed and came to me. I picked her up, put her back in bed and sat back down on the floor. It took about two hours of persistence but she finally stayed in bed and fell asleep.
A few nights of doing that and she now goes down easy.