As far as I am aware, as you have separate SmartTarget installations for Dev, Test, Prod, etc., there is (currently) no way of 'Content Porting' changes made to a Promotion in one environment into another - You will have to move these manually.
You can use the
Copy to functionality within SmartTarget 2014 (and later) to copy Promotions between different Targets (e.g. Staging and Live), but not between environments as you require. More details on copying Promotions can be found in the SDL LiveContent documentation (login required).
Moving them manually also ensures that all of the
Triggers that you are using are available in the target environment, and allows you to check that any IDs you are using are actually present too.