Regexp::Common has a mechanism that simplifies this greatly.

#! /usr/bin/perl

use strict ;
use warnings ;
$|++ ;

use Regexp::Common qw( delimited ) ;

my $str = do { local $/; <DATA> } ;

print "\nBefore\n-----\n", $str ;

$str =~ s/$RE{delimited}{-delim=>'"'}{-keep}/'$3'/gs ;

print "\nAfter\n-----\n", $str ;

exit ;

__DATA__
  "Welcome to my humble abode," I said, spreading my arms.
  "You mean, you live here?  In the monastery?"
  "Absolutely.  Come, I'll show you about.  Everything you need
is located right here, from tutorials to friendly advice."
[download]

_______________
DamnDirtyApe

Those who know that they are profound strive for clarity. Those who
would like to seem profound to the crowd strive for obscurity.
            --Friedrich Nietzsche