You can simplify all of the basic text responses by putting them into a table. Instead of:
if (message.content === "foo") message.channel.sendMessage("bar");
Do:
var responses = {"foo": "bar"};
if (responses[message]) message.channel.sendMessage(responses[message]);
It may be more complicated for shorter stacks of if else statements but it is more efficient for large ones like the one in your code.
