Clear fields when i change the Object in JSF

I'm from Brazil, and sorry for my english.

I have 2 classes with the same attributes. My inputs are bound with an Object, and when i click in a button i change the Object for the classes that i wish.

But, in the middle of the register i want to change the object for the other class (I make other instance)... NOW MY PROBLEM : when i change the object the fields continue with the same values. I need to clear all the fields.

I can't update the Form because i have required fields...

And again, sorry for the english :P