Juice up is an informal phrase that means to add excitement, energy or enthusiasm to someone or something. There are several synonyms to juice up, which can be used interchangeably. Some prominent synonyms include: amp up, pep up, liven up, spice up, rev up, charge up, invigorate, electrify, galvanize, stimulate, inspirit, enliven, refresh, animate, excite, vitalize, and energize. These words might have slightly different connotations, but all convey the idea of increasing energy levels, boosting enthusiasm, or elevating the mood. Using these synonyms can help writers add a fresh perspective to their writing and convey their intended meaning more precisely.