If you found any omission or wrong statement in the time of filling the return online in due time, he/they can re-file/revise  the return with necessary modification. This re-filing of the income tax return is referred to as Revised Return. The process for revising the return is very simple. Below given the process of how to fill the revised return:-

Revised return can be filed for any previous year at any time before the expiry of 1 year from the end of the relevant assessment year or before completion of the assessment whichever is earlier. For this financial year 2013-14), you can file the revised return till March 31st, 2014
However, if the income tax department completes the assessment of your return earlier, then a revised return cannot be filed.
Revised return can be filed only if the original return was filed before due date. Thus if a return is filed after a due date then it cannot be revised
A loss return filed within time can also be revised and in such case loss as per the revised is carried forward
One should have acknowledgement number and date of filing the original return in order to file a revised return
Return filed in response to the notice u/s 148 can also be revised. It should be noted that notice u/s 148 is issued in respect of the escaped income in the respective assessment year
In case of concealment of income and furnishing of inaccurate information in income tax return an individual will be penalized

How to file a revised return

Check for the discrepancy in ITR-V form received from the original return e-filing.
Go to the Income Tax Department's Web Site and choose the the home page,
 Login through link of Registered Users.
Prepare & Submit online Return under e-file & complete below detail as required.
1)  Enter the E-filing acknowledgement receipt number from the ITR-V (Which you got after the original return)
2)  Select the appropriate “return filed under section”. You will find options for 17-Revised 139(5).
3)  Press Save as Draft and continue and go ahead make changes and enter correct details
4)  Press Submit button on completion of data . You will get a new ITR-V marked as revised return.

5)  Once you receive the ITR-V form, you are supposed to send across both original and revised return ITR-V forms to IT department Bangalore within 120 days.