Comment by Jensson

Nah, you don't have to interview again, all you need is to look at open positions and contact a manager and if they say yes you got it, no hassle and you can start directly. It is good for both, you don't need to interview and the manager can see your performance reviews and code, so much easier to avoid bad engineers. Managers prefers internal candidates for this reason, so shouldn't be hard at all to find a new position unless you performed badly.