How to recover to default sets?

I have just a technical question. I would like to "format" my MacBook air. That means delete or personal data and set my Air to default.

When I did that last time I erased whole data. And when I would like to start system I have to downloaded firstly whole lion from internet and complete instalation took me about 4 hours.

Is there anyway how to delete whole personal data, but avoid to downloaded whole system from internet. Recover system from disk and after that make some updates? Is it somehow possible do that?

Please if so, can somebody provide me here how to do that?

Many thanks!