I just have my 2nd generation replaced by Apple . What I do to exchange it on 3rd and pay for the difference.nbn.

Hi

Apple currently offers a trade-in service for Apple Watch in certain countries.

Follow the links here (for the US, for example) for more information and to get an estimate of the trade-in value, based on your Apple Watch model and its condition:

• Renew and Recycling - Apple
• Apple Watch

If you are in a different country, then visit the corresponding page for your country instead, if available.

More information:

Identify your Apple Watch - Apple Support