Render again clears the finished picture off the screen. It does not delete it. The render is still in your Jobs history, and once it has completed it is on the Assets page too, and you can download it at full resolution from either.
Download first
The button beside it is Download, and it saves the picture to your device as render-result.png. Press that before Render again if you want the file, because Render again gives no warning and there is no undo.
What the button keeps
Your uploaded drawing, the render type, the model, the quality and the aspect ratio all stay exactly as they were. Only the result leaves the page. So the button is built for a second attempt at the same settings rather than for starting fresh: pressing it puts you back at the Render button with everything still filled in.
A second attempt costs a second credit
Every run is charged, and a repeat of the same drawing at the same settings costs the same as the first. There is no reduced price for trying again, so it is worth changing something before you spend the credit.
Finding the one you cleared
Open Jobs in the sidebar. Every render, staging job, upscale and edit you have run is listed newest first, and selecting a card opens the full picture with Download Full Resolution under it. Completed images are also on the Assets page, which holds finished results only.
Nothing on the Render page hints at either of these once the picture has gone, which is why the button reads as destructive when it is not.