I tried to explain this in my replies to both of your previous posts, but maybe I didn't put it clearly enough: your variables hold their values between requests because you are creating closures. You create a closure any time you run code under Apache::Registry that looks this:

my $foo = $query->param('foo');

bar();

sub bar {
  print $foo;
}
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Now you will never be able to change the value of $foo for that bar() sub.

It's easy to prevent this. You can pass the values to your subs:

my $foo = $query->param('foo');

bar($foo);

sub bar {
  my $foo = shift;
  print $foo;
}
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In addition to avoiding closures, it's simply a better programming practice. it improves abstraction and makes your code more robust. You could also put your subs in a separate module (a real module with a package name, not just a "require lib.pl" thing), which would force you to pass values to your subs.