Normally the types of "re-do"'s AF777 is mentioning, are when aircraft are due for a "D" check. This is one of the most thorough checks on an aircraft. As some of you might be familiar, the whole aircraft is stripped down; interior, wiring, various actuators, flaps, slats, rudder....you name it! The only thing remaining is the basic airframe. After disassembly, they install new wiring, sometimes new avionics..etc. This is a "re-do".
The only thing that remains old is the airframe, which with careful maintenance is perfectly safe.