My son was born with catastrophic injuries due to the delivery and what happened afterward I filed a suit for malpractice and withdrew without prejudice so that I could beat the deadline for the statute of limitations. This has been over 20 years ago is there a time limit when you can refile something like this?
Once you withdrew the complaint without prejudice, any statute of limitations benefit you obtained from filing the lawsuit evaporated. From a legal perspective, it is as if you never filed at all, except that the lawsuit that was filed proves that you had notice of the claim at the time you filed, so you cannot take advantage of any "discovery rule" that allows a statute of limitations to start running from the date that you knew or should have known of your right to file a lawsuit.
In all likelihood, the statute of limitations has now run, although that would depend upon the jurisdiction in which it was filed.
Some jurisdictions toll the statute of limitations during a period of minority, but that tolling might very well be insufficient to allow the claim to be filed 20 years later.