According to CBSE:
Candidates of NEET-UG 2013 can avail A ONE TIME OPPORTUNITY to correct personal particulars in the On-line Application submitted by them on the website www.cbseneet.nic.in.
This facility shall be available during the period 1st February, 2013 to 28th February, 2013.
Correction in City of Centre/Choice of Seats/Questions Paper Medium/Category/Nationality are not allowed.
After correction, Candidates may print correction slip and retain the same for reference and record.
Candidates are advised not to make any correspondence regarding corrections with the CBSE.
Status of receipt of Confirmation Page of Applications in the CBSE can also be viewed on-line on website www.cbseneet.nic.in with effect from 15th January, 2013 onwards.