use re 'eval';
sub limited_re {
	my $str=shift;
	my $re=shift;
	my $repl=shift;
	my $times=shift;

	our $cnt;
	local $cnt=0;
	$str =~ s/$re(?(?{++$cnt > $times})\A)/eval $repl/ge;
	print "$str\n";
}

limited_re("111111111",qr/1/,5,2);
limited_re("000000000111111111",qr/1/,2,5);