Last year just before DD(5) was to take a test to get into the private school that she is in now attends. I looked her dead in the eye and said "Girlfriend You Rock, you will do very good on your test". At that moment you could see the relaxation in her body and her facial expression changed. After the test was over she came skipping down the hallway, I knew she had done well. Come to find out later she, "Rocked the test"!
I'm not sure that will help your DD but sometimes just the right words give kids a sense of calm that everything is going to be alright!