I'm inclined to agree with atcroft. You can set the KeyRegenerationInterval in the script:

#!/usr/bin/perl

use strict;
use warnings;
use diagnostics;
use Net::SSH::Perl;

my $host     = 'host';
my $username = 'user';
my $password = 'password';
my $cmd      = 'ls -laR /some/directory';

my $ssh = Net::SSH::Perl->new(
    $host,
    protocol => '1,2',
    debug    => 1,
    options  => ["KeyRegenerationInterval 1h"]
);
$ssh->login( $username, $password );
$ssh->session_id;

my ( $stdout, $stderr, $exit ) = $ssh->cmd($cmd);
print $stdout, "\n";
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