my $current_time="00:02:25";
my $time_inc = 10;
my ($h, $m, $s) = split(/:/, $current_time);

$s += $time_inc;  ### 1 ###

$m += int($s / 60);  ### 2 ###
$s %= 60;  ### 3 ###

$h += int($m / 60);
$m %= 60;

my $new_time = join ':', $h, $m, $s;

print "$new_time\n";