I personally wouldn't use regex for this, but here you go. The secret is to make your entire address string match optional with (?:REGEX HERE)?

$_ = join '', <DATA>;
while (m/(.*)<br \/>\n(?:(.*)<br \/>\n)?(.*)<br \/><br \/>/g) {
    print "$1 - $2 - $3\n\n";
}

__DATA__
Name<br />
Address<br />
URL<br /><br />
Name2<br />
Address2<br /><br />
[download]