I will try to help you with your request.
Your design is independent from the amount of responses you measure.
Just add new columns to your design by double clicking into a new column field and track your results.
If you need to add a goal for every new response check out the "response limit" column property for you new columns and add a goal like "maximize" there.
When you run your model script in the upper left hand corner add your new response columns into the Y field.
Hope that helps.