Yeah you definitely need to start off slowly. Whenever I am trying to remember/relearn something I haven't played for a long time I firstly try and hear the piece in my head. Really listen to it. Then once I start trying to play it I'm often surprised just how easily it all comes back to me.
Sure there will be parts that require more memory jogging than others but, providing you learnt it correctly in the first place, your fingers should remeber what to play, even if you don't.
It's important to make sure that you are playing it correctly tho, as it's all too easy to start playing parts differently after a long lay off without realising it, so be sure to check what you're playing against the music notation, or the recording.