The answer to this question is really “it depends.” Most of the PaaS vendors offer replication tools that can take a standard Windows or Linux OS and spin up a new instance in fairly short order. Where it gets tricky is when you have customized your instance with a series of applications that depend on other operating instances in your cloud collection. These dependencies might not be well documented, or even obvious, and you might yourself trying to track them down when your applications don’t work properly.
For example, here is a tutorial on how to set up replication of MySQL servers on Rackspace and Google’s clouds:
A number of vendors have tools that can replicate an entire cloud VM collection, including Veeam and Cloud Velocity. Here is one example of the process using Dell’s AppAssure tool using AWS: