You can wipe out existing network and reestablish a new one by running

terraform destroy

followed by

terraform apply

from inside resources-tf.{network_name} folder. This requires access to Google Cloud Engine and properly confugired gcloud and terraform.

You can run nodes instances as preemptible VMs (which are considerably cheaper) when you need to make a short test. But their availability is not guaranteed.

To run preemptible instances (default), use in hosts.tf

preemptible       = true
automatic_restart = false

for usual one change config to

preemptible       = false
automatic_restart = true