Which phase of the customer life cycle categorizes customers according to value and attempts to win back high-value customers?

The answer is "loss/churn".

Marketing, customer acquisition, relationship management, and loss/churn are four stages to the customer life cycle.

Loss/churn refers to the last stage of a customer life cycle and this stage is loss/churn when unavoidably in time an organization may lose a customer. The company then needs to set up a win-back procedure. The company then needs to choose which lost customers are of most value and endeavor to win back their business.