There does not appear a way to retrigger from with-in the BlueOcean UI.

The re-run button preserves the Gerrit variables, but it does not interface iwth the plugin and thus no review is posted. Hard to direct users to the BlueOcean UI if they cannot re-run a failed job.

Perhaps a re-trigger button could be inserted view the "jenkins.blueocean.rundetails.top.widgets" extension point.