If you want people to know it's a question, yes. If it doesn't matter to the audience then no.
The reality is that while it's just a symbol, the question mark changes how people read the title. Like Dig It vs Dig It? one is an instruction and one is asking if you like it. If that is a vital thing that makes the thing make sense, then it's very important. If you wrote the lyrics, you can do what works for you, and the grammar police just have to live with it. I'm always very careful when talking via typing to use the ? so people read it correctly. If they say it, their voice gives it away at the end of the sentence - that doesn't happen in words on a screen?