The kubeconfig file is regenerated on every terraform apply that includes module.oke. To regenerate it without re-applying the full stack:

terraform apply -var-file=primary-<region>.tfvars -target="module.oke" -refresh-only

Alternatively, generate it from Terraform output:

terraform output -raw kubeconfig_yaml > kubeconfig-<cluster_name>.yaml
chmod 600 kubeconfig-<cluster_name>.yaml