A while back I found myself looking at a Unity scene with several hundred trees that each needed to be updated and the connection to the prefab had somehow broken... Rather than spent hours replacing each one I spent almost as much time writing an editor extension to do the same thing.
I'd forgotten about the tool, until a student of mine ended up in a similar position. Which made me revisit the tool a do just a bit of fine tuning.
|Screenshot of the editor window|
It's a pretty simple script, but handy all the same. If I find the time I might add it to the Unity Asset Store as a free asset. Until then, assuming this looks like useful, you can download it from this link (box). There's no documentation, but it should be pretty self explanatory- the search is case sensitive.