# Load in the whole file
open (FILE, "memberpoints.txt") or die "Can't read: $!";
while (<FILE>) {
	chomp;
	($name, $number) = split "-";
	$field ($name) = $number;
}

# Change whatever you want
$field{'vegeta'} += 6;
# ..etc

# Write the whole file back (replacing what was there before)
open (FILE, ">memberpoints.txt") or die "Can't write: $!";
foreach (keys %field) {
	print FILE "$_-$field{$_}\n";
}