You need to install it globally and execute it in the directory, where the package.json of your app is located at.
The tool will do a
git pull, rewrite/rebranch the dependencies upon your selected environment,
npm i the dependencies, find the app in the pm2 eco system and restart it.
$ npm i -g cr-deploy-app $ cd ~/git/myApp && cr-deploy-app
Integrate option to do a hard-reset in local repository, to throw uncommited changes away and get able to do a git pull.