But I've not found the answer anywhere else.

I'm using the command line to mirror my website and then weekly to update that
mirror.

As far as I can tell, the first time I use it, I add all the options e.g.

-K0 -s0 -A250000 -z -%A asp=text/html -F "Mozilla/5.0 (Windows NT 6.3; WOW64;
Trident/7.0; rv:11.0) like Gecko" -iC2

and then on subsequent runs I just use 

--update

Q1 is that correct?
Q2 how do I remove an option from subsequent updates?  i.e. I no longer want
extended logging, so I don't want the -z.  How do I remove it (without
deleting the whole mirror and starting again?)

thanks