Legal Question in Civil Litigation in California

All parties are supposed to file case management statements at least five court days before a case management conference. You do need to file a statement (unless the other side filed a joint statement with your consent), but your statement will be original to you and will not be a "reply" to your opponent's.

You don't file a "reply" but as Mr. Hoffman points out, you need to file a Case Management Statement of your own, or you could get sanctioned by the court. The Case Management Statement should be filed and served 15 calendar days prior to the Case Management Conference. (Cal. Rules of Court, rule 3.725 subd. (a).)

This should have been pointed out to you by opposing counsel when you met and conferred.