You should replace your neck pillow if you are not getting the support that you need. You may be waking up with headaches, a stiff neck or neck pain.
With fiber pillows they often need to be replaced sooner than foam pillows.
Also, a more firm pillow such as the tri core pillow (gentle or firm) is a very dense pillow, with the fiber packed into the pillow. Such a firm pillow does not work for everyone, but its great for those who prefer a firmer support pillow. These pillows will also last you long time, as it takes a long time for the fiber to break down.
Also one more note, get a dust cover for your pillow especially if you love the way that this pillow feels. Wash your dust cover regularly, and air out your pillows as well. Washing them just breaks down the fibers, so i don't recommend. Use your regular pillow case over your dust cover.
Here is a great pillow that provides great neck support. It is the pillow I sleep on every night. Personally I use a dust cover, that i wash regularly.
Arc4life Cervical traction neck pillow