42U Jetpack Booster is a addon for Jetpack by WordPress.Com plugin. It allows you to adds redirect tags and HTML email templates to your Jetpack Contact Forms.
For redirecting to your Jetpack Contact Form, simply add a text field named “redirect” to your form and it will be hidden on display. From HTML view, set the default value to the redirect location where you would like the form to get redirected after successful submission.
[contact-field label="redirect" type="text" default="/thanks/" /]
Remember to replace default each time after editing form with Jetpack WYSIWYG editor as the value is not saved by Jetpack.