Fertilizing herbs in containers?

I have my rosemary, thyme and oregano in containers, which didn't die off at all since I brought them inside over winter when the temp threatens freezing.

I just noticed the rosemary's new inner growth is a bit yellow.  This is due to lack of nutrients right?  I mean I transplanted that rosemary seedling back in August 2019 and now in April 2020 it's yellowing.

What's the best way to ammend soil in containers?  Should I take the root ball out and plant it into a new container with nutrient rich soil?  

I took a clipping of the rosemary a couple months back and rooted it.  It's now growing well in  a little seedling pot with nutrient rich soil.  Should I just preserve the plant this way and let the old one die off?  

Or should I use liquid fertilizer on the rosemary?   Or should I dig deep narrow holes and work in a mix of worm castings and organic fertilizer (Jobe's Vegetable and Tomato fertilizer is what I have).

If I were to amend the soil, I would only do it with a top dressing of aged compost. That will feed the biology and release nutrients as needed.

That said, some plants do have natural life spans and then die off. I am unsure of the natural life span of rosemary, but it seems taking cuttings and regrowing them seems to be working. So, I would stick to what works and ignore all the cost and hassle of trying to figure something out. That's just me though. I enjoy spending as much time as possible enjoying my garden and as little as possible working on it.

If it is indeed a nutrient imbalance, you may be able to pull some things from the bonsai realm since it is potted and in your home. Perhaps making a VERY weak nutrient tea and then spraying it daily would be helpful. Just another thought.

All the best,

I wonder about rosemary too.  I planted rosemary from a 4" pot.  It did ok the first year, growing a little.  The next year it grew quite large.  In the hot part of the summer some sprigs in the middle started to die, so I cut them out, and it seemed to be fine.  It's died back in the winters, and come back, but not this year.  It looks like it's a goner.
I just planted an herb garden, and it is my understanding once you start taking cutting or pieces of your herbs you should use something like a compost tea to keep it growing.  Time will tell, it's not much help to you, but it's what I will do.  Good luck to you