Hi TinaC,
If you intend to use the same brand and the same products over a long period of time, you will notice that after a while the products don't give the exact same results as from when you started using them. Certain products focus on one or more nutrients while they neglect the other. The best thing you can do is experiment and see if you can find other brand which give you a nice result just like your current products do now. Why does this happen? The new product may focus on other nutrients, so that it can balance the other nutrients that are now in your hair due to using your current product. So you can get a balance in those nutrients which are now in a lower amount available.
Experiment is the best thing you can do, but mixing different products together, that I never tried before.
Greetings.