Making changes to a draft Campaign

It's awesome that I can send out a Campaign Preview through the API, but how can I make a change if needed?  I can't see anything in the API documentation or the documentation for "campaignmonitor/createsend-php" that would allow this. 

Even if I had to delete and create a new one, I need a way to pull the content for the campaign to change.  Is there any way to do this?

200,000 companies around the world can't be wrong.

From Australia to Zimbabwe, and everywhere in between, companies count on 
Campaign Monitor for email campaigns that drive real business results.

Get started for free