Ableton Forum

On the left side of the screen, you've got your buttons to get to the "instruments/midi/effect", below that is "plugins", then below that you'll see the folders labeled "1,2,3". Click on any one of those and navigate to your previous Live set/track. You can click the arrows to look at each individual track and drag entire (single) tracks from previous projects or click on the down arrow and drag in individual clips.

nice thats a cool method i've never tried that before....alternatively you can do a 'save as' on your old project and delete everything but what you need for your new project and then drag the .als file from that into your new project. That will bring your 'save as' old proj into your new proj B-)