We can't publish a package twice to the npm, registry will check the package's version. Literally we can't update existing package, it will remain same.

Since packages need to be updated, we can use different version for new features, it also a good practice that the older version remain same, since there can be apps developed using those versions.

To publish a new version of the existing package, change the version key in the package.json (at the root of the project) and go on publish