helm upgrade -f ingress-controller/values.yml nginx-ingress stable/nginx-ingress
Or more generally:
helm upgrade -f new-values.yml {release name} {package name or path} --version {fixed-version}
The command above does the job.
Unless you manually specify the version with the --version {fixed-version} argument, upgrade will also update the chart version. You can find the current chart version with helm ls.
Docs: https://helm.sh/docs/helm/#helm-upgrade