An item that has been overcooked and must be replaced with a new item is known as:

The term "recook" refers to the process of preparing a dish again after it has been deemed unsatisfactory, typically due to overcooking. This term is widely used in culinary settings where food must meet certain quality standards. When an item is overcooked, it often does not meet the expectations for flavor or texture, necessitating its replacement to ensure that the final product served to customers is of the highest standard.

In contrast, the other terms listed do not accurately convey the specific action of cooking an item again due to it being overdone. "Upcook" is not a commonly recognized culinary term, and "refire" may imply a second attempt at cooking at a different temperature or method, but the focus here is specifically on overcooking. "Redo" is a more general term and lacks the specificity needed to describe the requirement in a culinary context. Thus, "recook" is the most appropriate choice for this situation.