Change part of a function name in multiple occurrences

Change the middle part of the function name in multiple places, preferably using the next and dot commands.

Input

call_this_function()

_this_
  
  call_this_function()

 _this_

 call_this_function()

Output

call_that_function()

_this_
  
  call_that_function()

 _this_

 call_that_function()