use strict;
my $str = '<li>
<a href="/WebRoot/products/8020/80203122/bilder/80203122.jpg">
<img
itemprop="image"
alt="Jesus Remember Me - Taize Songs (2CD)"
src="/WebRoot/AsaphNL/Shops/asaphnl/5422/8F43/62EE/D698/EF8E/4DEB/AED5/3B0E/80203122_xs.jpg"
data-src-xs="/WebRoot/AsaphNL/Shops/asaphnl/5422/8F43/62EE/D698/EF8E/4DEB/AED5/3B0E/80203122_xs.jpg"
data-src-s="/WebRoot/products/8020/80203122/bilder/80203122_s.jpg"
data-src-m="/WebRoot/products/8020/80203122/bilder/80203122_m.jpg"
data-src-l="/WebRoot/products/8020/80203122/bilder/80203122.jpg"
/>
</a>
</li>
</ul>';
my $regex = qr/(<img\s[^>]*?data-src-l\s*=\s*['\"])([^'\"]*?['\"])([^>]*?>)/mp;
my $subst = '$1http://www.asaphshop.nl$2$3';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html