Livener is a word that usually refers to something that makes people feel livelier and more alert. There are several synonyms you can use instead of this word. An invigorator is someone or something that stimulates or energizes. A tonic is a substance that invigorates or refreshes. A stimulant makes someone more lively or alert, while an energizer gives someone a boost of energy. A pick-me-up is something that makes someone feel better or more motivated. A reviver is something that can revive or reawaken someone's energy. A bracer is a drink that is believed to have restorative powers, while a restorative is something that helps to renew or restore energy.