Render Out Render Elements (Vray)

Hi i searched around alot for something like this but cant seem to find anything that can do exactly what i want. i want to be able to render out render elements singularly, often we have to batch render a project and the render elements are not saved, and its a huge mission to go back and rerender the shot to get the reflection render pass out (one that reflects the whole scene colour, as opposed to the reflection render in RenderMask).

kind regards
Sean