Generally speaking, a case that has been dismissed without prejudice may be refiled at any time until the time period to file has run out. In other words, most cases have a statute of limitations (a set period of time) within which the case may be filed. The time period typically starts running from the date the event at issue happened. If a case is filed after the time runs out it may be dismissed as being time barred by the statute of limitations. However, this defense must be raised immediately in response to the filed action or the statute of limitations defense may be deemed to have been waived. Statutes of limitations vary by state and by type of claim. You will have to determine the statute of limitations for your specific case to determine whether it may be raised as a valid defense.