If you wish to scale out an existing cluster, we can do it with a few steps. Manually scaling up your cluster on GCE is actually quite easy. The existing plumbing uses managed instance groups in GCE, which allow you to easily add more machines of a standard configuration to the group via an instance template.
You can see this template easily in the GCE console. First, open the console; by default, this should open your default project console. If you are using another project for your Kubernetes cluster, simply select it from the project dropdown at the top of the page.
On the side panel, see under Compute and then Compute Engine, and select Instance templates. You should see a template titled kubernetes-minion-template ...