Q.Growing Cilantro Year Around
I had a very successful summer growing my cilantro. However, the stems got very thick, no longer a bushy plant, kept it trimmed and kept all seedlings off to keep the plant going. Now, it doesn’t have hardly any regular leaves that it did and the plant has just thick stocks.

Certified GKH Gardening Expert
Once it does this, you will want to start over. Cilantro isn't meant to live for more than a season, being an annual.
This article will help you to grow cilantro:
https://www.gardeningknowhow.com/edible/herbs/cilantro/tips-for-growing-cilantro.htm