The last version to date is 2.3 and the 1.13.15 is installed on my machine. How do I nice-update to 2.3? Unistall the current first?
Each set of Ember CLI Releases comes complete with upgrade instructions:
Releases - ember-cli/ember-cli
If you're looking to upgrade both Ember CLI, Ember, AND Ember Data I'd suggest upgrading to each minor revision starting at 2.0, fix all of the deprecation warnings, and then proceed to the next release.