Without knowing how the chatbot's code looks, this is a difficult question to answer. I can't just tell you "add this code" because I don't know where or how in the script it needs to be added. At a very abstract level, what you need to do is create a list of keywords that you want the chatbot to respond to, like "travel". Then you need to associate a response with each keyword. I'd do this either in an associative array or a database, depending on how many keywords you have. Then have the chatbot watch for the keywords, and when one comes up, return the appropriate response.
I'm sorry I can't be more helpful, but this isn't a trivial matter, especially since we can't see inside your chatbot script.