Well, if you are already preparing a replacement of something/someone, incase it/he wouldn't continue to do what it/he should do and currently is doing for you, can you call that activity "arranging a back-up"?
So is a conversation like this possible?
"Tom is planning to leave the country, so in a few months maybe you have to start doing your own homework!"
"Don't worry, I'm already arranging a back-up (=I'm already looking for another)."