You can use a catalog UI policy for this (you are probably already using one to show the extra fields for a 2nd/3rd year.
Make sure the 'Reverse if false' field is true and the 'Run Scripts' field is true on the catalog UI policy and use this code in the execute if false script:

function onCondition() {
//Clear the fields if 'No'
g_form.setValue('your_field', '');
g_form.setValue('your_field2', '');
}