Are you using a text editor that can't index your repo and do search-replace within? Vim and emacs both do this easily.

If you're not using an IDE, have you considered that by DRY-ing up constants, you're adding about 2-3 steps to even see what the value of a constant is?

Jump to the top of your file, figure out where the import is from, open the other file, then find constant name.

You also force your code reviewers to do this in e.g. GitHub, where there's no convenient 'jump to definition'.

IMHO, if your starting point is that you won't use sed, can't use a good IDE, and won't configure your editor nicely, then you're just creating a lot of unnecessary work for yourself, regardless of whether you're doing DRY.

Power tools are appropriate if you're building a house.