How do I withdraw money from BitPay?
According to their support site it should be on it's way without you doing a thing. I quote:


  If you choose to take settlement in bitcoin, BitPay will forward bitcoin payments to your bitcoin address on file. The minimum settlement is 0.01 BTC.


Maybe look on blockchain if there is an unconfirmed transaction to your address or reset Multibit if you are using that. Or you haven't hit the minimum settlement of 0.01 BTC.