How to recreate GCP Preemptible VMs behind LB before they expire?
Strictly you can't do this with a single preemptable virtual machine as you only get a 30 second grace period. While the majority of calls to the Google Compute Engine API would create a new device within 30 seconds, there are cases when this would fail due to network latency or temporary outage.

What you can do is create an Instance Group of Preemptible Virtual Machines with a minimum of two instances, the probability of GCE killing both at precisely the same time is quite low, and once GCE destroys one a new one will be created to bring the IG instance count back up to two.