Dear Rohan,
The most important criteria for appearing in IIT JEE this year besides percentage in 12th and date of birth is that, you have to be passed in your qualifying examination ( i mean 12th class or board examinations which ever is applicable ) for the first time, after october 1,2008 or in 2009 or will be appearing in 2010. So, on the basis of this information your sister will not be able to do second B.Tech in any of the IIT's.
If you are so keen of getting into IIT's, it would be best if you write GATE by which you can get into IIT for doin M.Tech in your branch.
Please feel free to post as many doubts on our discussion forum as you can. If you find any question 
Difficult to understand - post it here and we will get you the answer and detailed solution very quickly. We 
are all IITians and here to help you in your IIT JEE preparation. 


All the best Rohan !!!




Regards,

Askiitians Experts
Rohith Gandhi
						

							Hi Rohan,

Yes ,  your sister can give the Graduate Aptitude Test in Engineering (GATE)

Graduate Aptitude Test in Engineering (GATE) is an all India examination administered and conducted jointly by the Indian Institute of Science and seven Indian Institutes of Technology on behalf of the National Coordination Board - GATE, Department of Higher Education, Ministry of Human Resource Development (MHRD), Government of India.
It is for admission into the post graduate programme in Engineering at IITs

Regards, 
Rajat
Askiitians.com Expert