Reason for my vote of 2
There are other ways to refresh the browser page than by pressing a specific key. Technically, even that would be browser-specific, although I suspect that there's an informal consistency in key mappings between browsers nowadays.
The only certain way to achieve this is to ensure that the back-end server can cope with receiving the same post more than once (as the OP example demonstrates).
Last Visit: 31-Dec-99 19:00 Last Update: 3-May-16 8:09