Berkeley DB Family

How can I do to evolve the db of my system?

For example, I had a class with some attributes, see the example:

...
private String name;
private Integer age;
...

and now I want remove the "Integer age" attribute and add the "String hairColor".

When I make this change in the class and in the bind interface of this class, JE returns to me Java exception, like a OutOfBounds Exception.

What is the correct form to change my DataBase?