revive
To bring something back to life, strength, or energy.
To revive means to bring something back to life, consciousness, or strength after it has weakened, faded, or stopped. When paramedics revive someone whose heart has stopped, they restart it and restore the person's breathing. When you revive a wilting plant by watering it, you help it recover its strength and stand up straight again.
The word works for many situations beyond literal life and death. A director might revive an old play by staging a new production of it. A baker could revive a family recipe that hasn't been made in decades. Cities work to revive struggling downtown areas by bringing in new businesses and activities. After running hard in gym class, you might need to sit in the shade and revive yourself with cold water.
Related words include revival, meaning the act of bringing something back (like a revival of interest in folk music), and revitalize, which means to give new life or energy to something. When archaeologists discover an ancient language and teach people to read it again, they help revive the language. When you feel exhausted but then get your energy back, you've been revived.