PAT test void on dismantling the plug?
Technically, you don't have to do any PAT testing at all, but of course, your insurer requires it. 

PAT FAQ

I would say that if you are considered a competent person to do the work you just did, you would probably be fine. If the device previously passed PAT testing, and you haven't damaged the plug or wiring in any way I'd be comfortable in saying it was still safe.

If your manager want's to pay for additional testing thats their problem though.