Complex sentence: Wendy's reformulated their grilled chicken product in 2004 as the Ultimate Chicken Grill sandwich during an overhaul of its chicken sandwich line and as of November 2013 it is still the chain's main grilled sandwich in the United States.
Split into simpler sentences: Wendy's reformulated their grilled chicken product in 2004 as the Ultimate Chicken Grill sandwich during an overhaul of its chicken sandwich line. As of November 2013, The Ultimate Chicken Grill is still the chain's main grilled sandwich in the United States.