The word "re-serves" could have a variety of antonyms depending on the context. If we are talking about serving food, then the antonym could be "withholds," "refuses," or "denies." If we are discussing a sports match, then the antonym could be "returns," "rejects," or "rebounds." In a legal setting, the antonym could be "forfeits," "loses," or "renounces." In a customer service context, the antonym could be "ignores," "neglects," or "abandons." In essence, the antonyms for "re-serves" depend on the situation in which the term is being used.