3-4D Ultrasound

We had our first 3-4D US at 29 weeks our baby would not show his face, he had his hand on his face and was using my placenta as a cushion. We have returned two other times with no success, baby would not move enough for us to see his face.  Today is our last try.  I'm now 34 weeks which is pretty far out for an US.  How do I get this little guy to move? We've tried cold water, juice, ice cream and coffee. Any other suggestions?