If you run it without /e you will notice the string becomes `printhi`. Now you want to eval this expression and the /e takes care of that.

This works for me

 
#!/usr/bin/perl

use strict;
use warnings;

my $str = "printmeprinthi";

$str =~ s/printme(.*)$/`$1`/e;

print $str,$/;
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my printhi program is

#!/bin/sh
echo hi
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output

hi
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