I would advise against re-using your plates.  If you want to repeat the experiment, use freshly coated plates to avoid any non-specific interactions/results.  If the affinity of the antibody/antigen interaction is high enough to show you some positive OD readings, then you won’t be able to take the antibody off easily. It may be possible to apply a low pH solution (e.g. pH=3-3.5) to dissociate the Ab-Ag complexes, but, in your case, the uniform coating of the oligos on the plate is important, and it will not remain uniform after such manipulations.