As a frequent visitor to Chinatown, I'd say that an easy way to get folks in there after dark would be to add some bicycle parking in the square. Presently, there is exactly none--all you can do is try to lock to a bench, grill, or grating, which inevitably puts you in someone's way.
LA's cyclists have a vast and well-developed night life--my son's rides with his groups and buddies often go till 4AM, and almost always go downtown. They get pretty hungry riding around. Crowds of hungry and thirsty cyclists hanging around would certainly inspire bars, cafés, and restaurants, at least, to stay open later. And bike parking is cheap and takes up almost no space.
I'm nearly sixty, and ride everywhere, and would love to spend more of my time and money in Chinatown, which I love, but there's far less bike parking than car parking there. How about making all us hungry cyclists feel welcome? According to the official Chinatown website, there are eleven parking lots or structures within Chinatown--eleven! Give us a place to lock up, too, and we'll be there--and you'll be getting far more bang for your parking buck from cyclists.