my $ftp = Net::FTP->new("XXX.XX.XX.XXX", Debug => 1, Port => 21, => Timeout => 300);
my $num_tries = 0;
my $max_tries = 5 #you decide how many times you want to try

while ( !$ftp) {
    if ($num_tries< $max_tries) ) {
         ++$num_tries;
         $ftp = Net::FTP->new("XXX.XX.XX.XXX", Debug => 1, Port => 21, => Timeout => 300);
    } 
    if ($num_tries >= $max_tries) ) {    
         croak "Cannot connect to host, failed after $num_tries times : $@"; 
    }
}