If you remarry your ex, will the divorce decree become null and void?

No. It is a new marriage and the date of marriage and any date of separation will not count the first marriage.

Here is a case synopsis THAT MAY NOT BE RELIED UPON AS THIS IS A GENERAL ANSWER AND EVERY CASE MAY BE DIFFERENT that describes THE FOLLOWING ABOUT REMARRIAGE AND PAST COURT ORDERS. Davis v. Davis (1968) P.2d 502-508. In Davis, the Supreme Court held that after remarriage of divorced parents to each other, neither could enforce against the other any support orders made in the prior divorce proceedings. The court went on to state that if the parties to the divorce again intermarry, child custody and support orders as between themselves are thereupon terminated as well as the jurisdiction of the court to enforce such orders, and that this is true whether or not the parties subsequently divorce again. When you are dealing with fragile economic issues in court, competent legal representation should always be sought, as the subject matter of the litigation is so very important. One mistake here could cause the biggest adverse consequence of your life!