Complex sentence: The re-release of "Overcome" in December 2010 included new songs which were not included on the original album, and included collaborations with Cobra Starship on "What Happens on the Dancefloor" and with Laza Morgan on "Start Without You".
Split into simpler sentences: The re-release of "Overcome" in December 2010 included new songs which were not on the original album. They included collaborations with Cobra Starship on "What Happens on the Dancefloor" and Laza Morgan on "Start Without You".