First of all, you must understand that in the cadastral passport indicates the floor area without balconies and loggias (housing code)
Technical - the entire premises, each separately and without balconies and loggias.
The cadastral passport is made on the basis of the technical passport and measurements specialists BTI.
If the discrepancy still exists, then it may be a technical error. You should contact the authority which issued technical passport for the apartment, it is possible that at the time of issuance were some standards include the areas, which are included in the Technical passport, and then they changed, and in the cadastral passport appeared other data.
Also one of the variants of solving this problem: to ask a question about the discrepancy in the Cadastral chamber, and then in BTI - if it's just a technical error, they are obliged to fix it.
It is not excluded the case that you may need to re-measure the premises, there must be a clear identification of the square, under which it should be made re-registration of all documents. But in this case, most likely, you will need to pay extra for the service call specialist.