How to replace instance names easily?

In the first frame I have 60 buttons with each having a actionscript in it using the instance name “A1”. What I need to know is how can I REPLACE the instance name from A1 to B1 in 60 buttons in my NEXT FREAME?

Is there an easy way to do it rather than typing one by one?? I used the “FIND AND REPLACE” option but it replaces A1 to B1 in both the frames. I need to alter the instance name only in the second frame. How can I do it???