They should still be open, but they will be week. So you don't have to do the first Opening the Chakras meditations again. You could do this if you want, but I don't think it is required.
But you do have to work on each of these chakras. A good way is by doing the Tuning Chakras through Vibration. With the set of mantras that all end with AUM. You should do this for each of your chakras until you are feeling that they are open. And practice breathing the energy through them, you will start to feel the energy flowing through them as you are breathing. You might not be able to feel this at first, but you will feel it when you have more practice.
The Final RTR is another thing that helps to remove blockages from the chakras so they can flow better.