I usually put an announcement step with a generic change announcement (e.g. our menu has changed, please listen to all options before making your selection) before my collect step. That way you can still keep your menu announcement in one announcement, you can use that generic menu changed announcement whenever you change a menu, and you can remove the menu changed announcement at a later date. I usually leave them on for 2 or 3 weeks depending on the type of call your getting and the people calling the menu.
Hope that helps.