"Re-serve" simply means to serve again, but not all words can be paired with an antonym. In this case, a fitting antonym for "re-serve" would be "discard," meaning to get rid of or throw away something. While "re-serve" implies a second chance, "discard" denotes an action of disposing something completely. Other possible antonyms could include "deny," "reject," or "withhold." However, it depends on the context in which "re-serve" is being used and what exactly is being served. Overall, finding an antonym for any word requires an understanding of its meaning and how it's being used in a particular context.