Problem with connecting vertices

My model has a layer of ‘clothing’ over a figure of a person. In removing some vertices I didn’t want I accidentally removed a patch on the other side. I reconnected the vertices where the hole is using extrude and alt-m, and it looks and acts re-connected. but when I render it the hole is still there. How do I make the hole fill in again? thanks.

have you checked for flipped normals?