You can make a motion to re-new but you have to show that you could not have gotten the affivadivit the first time by using due dilligence. You can also appeal if there are grounds. Discuss this with your lawyer.
I am a former federal and State prosecutor and now handle criminal defense and personal injury/civil rights cases. Feel free to check out my web site and contact me at (212) 577-9797 or via email at Eric@RothsteinLawNY.com. I was named to the Super Lawyers list as one of the top attorneys in New York for 2012. No more than 5 percent of the lawyers in the state are selected by Super Lawyers. The above answer is for informational purposes only and not meant as legal advice.
It depends on the timing of when the case was dismissed and when the order was entered. You could possibly make a motion to re argue the defendants motion but you would have to prove a justifiable excuse for your failure to have an expert affidavit in your original opposition papers. Why didn't you find a different doctor - an expert witness to do an affidavit in opposition? An appeal will not succeed because the papers submitted create the potential record on appeal and are not enough to reverse the underlying decision.