Please re-read my post. I said to bring in a new species meaning a new playable race that is not already in the game. I mean, they'll probably recycle other voiceovers in the game for it, but if they were professional about it they would make a new voiceover for a new species.
For example: Bring in Trandoshans and you need a new voiceover. I don't know if Trandoshans are capable of speaking English (or whatever it's called in the Star Wars universe) but you would need a newvoice over anyway.