What happens when I delete rendered video

"Renders" ... are simply preview files. Deleting renders doesn't have any effect on a timeline other than perhaps slowing playback.

"Render and replace" is an entirely different process, where it encodes a new file to replace the original clip on the sequence. The way to get back to originals from R&R is to right-click "restore unrendered".

So ... do you mean previews made by simply rendering from the sequence, or new media made by doing a render & replace?

Neil

Let's get the terminology straight so that we can fully understand the issue:

Render in Premiere Pro means to create preview files by pressing Enter on the timeline or by Sequence > Render Work Area from the menu.

Exporting is the process of creating a stand alone file for external viewing or for reimporting into Premiere Pro.

Please explain more clearly exactly what you are trying to do.