I think you can do so if you cover the unused well in the plate well, because the coated Ag or Ab is remain intact if you protect them by covering.

best wishes

Thank you so much!

Yes, you can reuse the wells of an ELISA plate that have not been exposed to air or to any of your reagents. Next time you purchase your plates, buy those with removable wells so that you can take only the wells that you need to use and leave those that you don't need in the package.

You can see how they look on this website: https://www.stellarscientific.com/nest-scientific-high-binding-elisa-plates-detachable-wells-5-pk-50-cs/?gclid=Cj0KCQjw_r3nBRDxARIsAJljleH0UD26XFpkPlfobLeMLlLTKKf1S6IvOpmsPuWsjM0JUOlrSbsf56saAlDWEALw_wcB