Can I update cordova CLI and ionic CLI to latest version?

Hi all, I’m new to the forum.

I currently have five applications developed with ionic 1 version.

My ionic info:

Cordova CLI: 6.4.0 
Ionic CLI Version: 2.1.18
Ionic App Lib Version: 2.1.9
ios-deploy version: 1.9.0 
ios-sim version: 6.1.2 
OS: macOS Sierra
Node Version: v6.9.4
Xcode version: Xcode 9.0 Build version 9A235

I would like to upgrade to the latest versions of Cordova CLI and Ionic CLI. The question is: if I update Cordova CLI and Ionic CLI will my old applications still be modified and built without having to rewrite them from scratch? What kind of changes will I have to make to the configuration/code?

Thanks in advance for your help.