How to force a total WiFi connection reset?

[Chris Green]

I have a large house and have a second (old) router working as a WiFi
access point to improve coverage.

When moving my laptop (running xubuntu 18.04) around the house it
refuses to 'let go' of a weaker wifi signal in favour of a stronger one.

Is there any way I can make Network Manager completely reset the WiFi
connection such that when reconnecting it finds the best signal rather
than using the last one it had?  Simply hitting disconnect and then
reconnecting doesn't work.

-- 
Chris Green