You can set the current renderer to scanline, then back to VRay. That way you don’t need to exit the file.
OR
Open the maxscript listener (press F11 on the keyboard or right click in the pink block bottom left of the screen and choose “open listener window” and paste this in there:
renderers.current=vray()
Press enter and it will reset the VRay rendering settings to default 3.3
You can also highlight the line you just pasted, and drag it onto a toolbar to automatically create a button for you. Next time you can just click that button