Well, if all your files are uniform, such as my expire is set to 604800 and my minimum is set to 38400, these are all unique numbers within each file, you could do a sed to change them.
Something like this:
for i in `ls *.net`
sed -e 's/604800/666666/' \
-e 's/38400/33333/' $i > blah.tmp
mv blah.tmp $i
If they're not all uniform, then you can do something with head and tail and some echos...but hopefully the simple sed script will work for you.