Hi, please try the following
http://cordova.apache.org/docs/en/3.6.0/guide_platforms_win8_upgrade.md.html#Upgrading%20Windows%208
1. Update cordova CLI to the latest version (npm update -g cordova)
2. cd to your app
3. Run 'cordova platform update windows8'
Thx!
Sergey
-Original
Hi Kartik.
Do you want to update CLI or platforms. Either way here how you can do it
*Updating CLI*
npm -g update cordova
*Updating platforms*
cordova platform update platform
Do this update for each platform you have
Source: