It's a slang term http://www.urbandictionary.com/define.php?term=hook+it+up

"to hook something up" is to connect something to a power supply. It's slang. e.g. "I hooked up the computer to the network" If you had a lot of equipment which you need to connect to power supplies, you could command your friend to "hook it all up" I don't know if this is what she means in the song as pop lyrics are not always well expressed. "Hook it on up" is not an established phrasal verb and I have never heard it said. I'd have to listen to the song to guess the meaning from the context. It may be a newly-coined verb or one with no clear meaning, as is typical in many pop songs. (e.g. James Brown "get up, get on up"). By the way, "to hook up with" is to meet or connect with someone. It is also slang. It can imply a romantic relationship depending on the context.