Complex sentence: Jepsen first performed "This Kiss" on "The Ellen DeGeneres Show" on September 18,2012, and later the same day on "So You Think You Can Dance" season 9 finale.
Split into simpler sentences: Jepsen first performed "This Kiss" on "The Ellen DeGeneres Show" on September 18,2012. On September 18,2012, Jepsen performed the song on "So You Think You Can Dance" season 9 finale.