What you're probably looking for is a way to load data into your template from variables. But you're going about this the wrong way. Use a hash to store the data, and regex to substitute:

use strict;
use warnings;

my %vars = (
    var1 => 'MyValue',
);

my $here_is = <<SOME_TEXT;

    I want to print something 
    with a value %var1%
    and some other text load
    etc etc

SOME_TEXT

$here_is =~ s/%(\w+?)%/$vars{$1}/g;
print $here_is;
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You may also want to look at loading the template from a file or __DATA__, so you're not forced to allow the extra line break that <<TAG makes mandatory.