I may now what bsaksida thinks. (For example Ref++ have this feature.)
Let see what I mean:
void Something(void) { int a = Q*X*G*2; int b = Q*X*G*5; }
When I choose extract method for "Q*X*G", VAX could replace all occurrence of this expression after a question or something. For example you can place a checkbox to the extract method dialog to replace other occurrences of this expression in the same scope. If no other occurrence(s) found the checkbox should be disabled.
(Sometimes when I cloning some line of code by copy-paste and later I using Extract Method, I have to find and replace the other occurences of these lines. It's no great matter, just mentioned )