Interest exemption under income tax act section 24b

Top up loan on my existing home loan

it means u r taking new loan which u already use 

and u use it again for same house 

interest may be allowable subject to proper bills 

Only 30000 available..
*If a person take loan for acquisition or construction of house Property and acquisition or construction completed within 5years from end of the year in which loan taken** only then he is eligible for higher deduction of Rs. 2L.
In your case *loan is for Reconstruction as well as for renovation* means ineligible..