To "revive" something means to bring it back to life, or to make it healthy again after it was sick. Here are some things you can "revive":

• a plant that was almost dead
• a trend that's gone out of style
• the economy of a country that's been weak for a while

In the example above, some people hope that the city will "revive itself". That means that the people of the city will make the city rich, safe, and healthy again.