The Change of Location upgrade option allows you to change the city where your ad is posted as often as you like for the duration of the option.
This option can be purchased from your ad as part of an upgrade. Login to your account.
Click on "My Ads"
Scroll to the ad that needs to be updated and click "Add Upgrades"
Select "Change City", pay for the upgrade, and you would be able to change the location when editing the ad.
If need help getting started, contact Customer Support and they’ll guide you.