Hello Notmuchers

What is a good way (with emacs) to hook into the search to modify only a
part of a search term. I find myself often doing this:

    date:2d.. not is:rfile

rfile is my tag for mails that i archive locally. I am looking for a way
to query myself only for the number of days in the minibuffer. I use
this search to filter off all mailing list stuff from a search. So, in
the above example I would only have to answer 2 .

Sunny regards
--
Tomas