Usually when new version of Node.js comes out and you update it by just installing new and removing old one, all of your global NPM packages are gone. Here is how to update to new version of Node and reinstall packages:
$ nvm install NEW_VERSION --reinstall-packages-from=OLD_VERSION
$ nvm install 7.4.0 --reinstall-packages-from=7.3.0
$ nvm uninstall OLD_VERSION