This is one of the features that are missing for the whole time after vRA 8.x was relased, so almost 2,5 years now, along with unregistering and changing owners of deployments after onboarding.
You could force a deployment to redeploy after making changes, using a deployment (resource?) parameter, however from my experience this would result in: redeploying on almost every change or not redeploying on any change.
Since there is no universal "redeploy" action, you have to find the right combination of correct resource parameters and an action, that would change the deplyoment in a way to force a redeployment.
So far I have not found a solution for this, either you end up with small changes triggering a redeplyoment, which you do not want, or break the plan update with changes that you want to trigger a redeplyoment with. An example would be changing the base image of a deployed virtual machines: say you use an Ubuntu 20 image and add the option to use Ubuntu 22 in your templates (for vsphere.machine). Users which deplyoed their Ubuntu 20 systems using the template would now be able to select Ubuntu 22 in "Update Deployment". This would trigger a redeployment, however when you configure your template like this, other miniscule changes, like editing the NIC configuration, would also trigger a redeployment.
