updating a deb

[Filippo Basso <debian@zirak.it>]

Hi all,
   I'm now playing with deb files, and had a nice day making my first 
deb, and my local repository...
Just a problem: if I update the deb (correct the problem, dch -i, and 
again dpkg-buildpackage), simple apt-get update doesn't work, I need to 
purge it before...
it's like it consider all files as conffiles!

what have i to do, to update pippo_1.0-1.deb into a pippo_1.0-2.deb so 
that I don't have to do
"dpkg -P pippo" before reinstall ?

thank you,
   please cc: debian@zirak.it