I've been using this word to describe the San Vito from Villa Monteleone, so I thought I'd give you the first part of the definition provided in the Oxford Companion to Wine:
Italian term meaning literally 'repassed', for the technique of adding extra flavour, and alcohol, to valpolicella by re-fermenting the young wine on the unpressed skins of amarone wines after these dried grape wines have finished their fermentation in the spring.
Though this is the "proper" or legally defined way to produce ripasso, a sort of "baby Amarone" (as it's been described), a more expensive and better-quality option is to use dried grapes that are being used for the first time, which cuts the bitter tannins that result from the strictly defined ripassimento.
I prefer ripasso to Amarone, in general. It's more balanced, less sweet, usually has less alcohol and accompanies a meal far more pleasurably than Amarone. Ripasso you can drink all the time; Amarone has to be reserved for special times -- cold weather, big heavy dishes, holidays. And then there's its high cost. To my mind, ripasso is a far better deal for the really smart winelover.