Suppose you have

name foo

and you want to leave all the various configurations for foo exactly as they
are now, but want the IP address to change to

there appears to be no "change existing name"; this is what happens:

ciscoasa# conf t
ciscoasa(config)# name foo
ERROR: 'foo' is already mapped to!

If you make the change using the ASDM gui, however, ASDM will take care of all
the fiddling for you. (Hint: to make sure it's doing the right thing, turn on
"preview commands before sending to device" in preferences.)