src/Extensions/GridFieldBetterButtonsItemRequest.php
public function doSaveAndAdd($data, $form)
    {
        return $this->saveAndRedirect($data, $form, $this->owner->Link("addnew"));
    }
public function doSaveAndAdd($data, $form)
    {
        return $this->saveAndRedirect($data, $form, $this->owner->Link("addnew"));
    }
Saves the form and forwards to a blank form to continue creating

@param array The form data
@param Form The form object