Refund of additional TDS on already processed e return

[subbufca]

Sirs,  AN assessee   filed his return electronically and made a claim for refund of excess tax  for the year ended 31.3.2013 based on the tax credits displayed by 26AS. Th return was processed, intimation u/s143(1)(a) sent  and refund received. On regularization of TDS defaults by awarer (the income whereof has been already considered in return filed ) , additional  TDS amount get reflected  in 26AS of the year as at present. How the assessee could claim this additional TDS -whether by fresh e-return  or by direct request to the AO?If e-return how the refund already received is to be shown 

With best regards
K S Iyer