Can I replicate a campaign?

Yes!

To do so, while creating the campaign you'd like to replicate later, be sure to save it as a template.

Afterwards, when you create a new campaign and reach the message step, select Use a saved template and select from the drop down.

NOTE: You are not allowed to replicate a whole campaign (including replicating the contacts the campaign went out to). This is to prevent 'accidental broadcasts' intended for other audiences.