Can I re-use an elastic (Stretch-Fit®) multiribbed belt after it's been removed? 
Yes, providing: the belt has not been damaged during removal, original rotational direction is the same and the belt is still in good condition. Be sure to use the correct installation tool and follow the installation instructions printed on the inside of the belt sleeve. Gates have also developed a free tool which can check if the belt is worn and should be replaced, ask your Gates supplier for a free ABDS Wear Indiciator Tool.