Since I'm not yet the regex master I aspire to be, I can't authoritatively state that this solution is better, but it seems to work.

If you're working with ordered item labels you can make your assertion more specific:

$n = 1;
s/((??{$n+1})\))(?{$n++})/\n$1/g;
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The first iteration matches "2)" and replaces it with "\n2)", the second "3)", and so on.

conv

Update: I should know better than to post when I'm tired. Someone just pointed out to me that it would be much neater to do:

$n = 2; ++$n while s/$n(?=\))/\n$n/
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Thanks, Aristotle, you're right. The while loop substitution isn't equivalent because it will make replacements in any order (at any position in the string) while the original substitution I posted will not.