I have a landscape bed that needs reviving. My question is do I pull up all the rock and put down new fabric? Or do I just add more rock? The bed is about 8 years old.

Welcome to the site!
Where approx is your geographic location?
Personally I do not use rock mulch, it makes it difficult to grow plants because of the heat sink it causes, additionally I think if you do try to pull up the fabric you will see that most if not all of the holes for moisture and air are blocked by the rock fines. Shredded bark mulch would do the same job but would be better for any plant growth and it makes it easier to pull any resulting weeds, plus much better for the soil. Personally would not use a fabric.

Are you wanting to "plant" the bed?
If so, then I'd remove the rock, and the fabric...add compost, if you have it, or can buy "garden soil".

Guess it all depends on what your ultimate goal is for the bed...

I'm not a fan of gravel. It might look nice-ish the first few years, but after a while dirt and organic matter blown/washed in by wind and rain collects between the particles and essentially creates soil that grows weeds. So landscape fabric underneath is a total waste in that regard too (it doés help in keeping the soil and gravel separated and prevent the stones from sinking into the soil).
It's also a hassle to plant in indeed: remove gravel, cut a cross and flip over the fabric, dig the hole and dump it in a bucket (because of reasons mentioned above), backfill, flip fabric over again etc....just sucks the fun out of the best part of gardening really.

If I were you: gone with the lot and start fresh on actual, good ol soil

But why does it need reviving? What specifically is going wrong?

Thanks everyone for your input. I was trying for the easiest. It is an existing bed that already had rock in it. There are established plants already there but the weeds are taking over because of driveway run off and the rocks have settled over time.