How often should an eechocardiogram be done on an individual with chf?

It depends: Usually echo is done to assess function, and is based on some change (often for the worse) prompting this question. "routine" echo could be annually or longer, depending on function level where starting from.

Depends: A regular follow up echocardiogram is not necessary after the initial echocardiogram has established the nature or cause of your CHF unless your condition has changed or a procedure has been performed .If you are doing well, whatever the echocardiogram shows will not matter in your care.