Once you've already got the bond, you're in a much better position to negotiate as it's much easier to move a bond than to get a new one.
My Colleague and I approach the banks every five years to see if anyone's interested in our bond. Last year, my Colleague moved one of her properties that she has had for 5 years from a bank to SA Home Loans. They waived the admin fees, so the only fees my Colleague had to pay was the bond costs, and that they included in the bond. They dropped her interest rate by 2%, since she was above prime rate with the other bank.