XML is better handled by an XML-aware tool.

#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

use XML::LibXML;

my $content = '<entry key="maxcompdatastripe" value="41943040" />';

my $entry = 'XML::LibXML'->load_xml(string => $content)->documentEleme
+nt;
$entry->{value} = '20917520';
$entry->{merge} = 'keep';
say $entry;
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