The new owners of a Las Colinas office tower have completed substantial renovations to the property. KBS Real Estate Investment Trust said Wednesday that it has remodeled the 19-story Tower on Lake Carolyn office building which has been renamed Tower 909. In late 2012 California-based KBS paid $46.3 million to purchase the tower, which is located east of State Highway 114 in Irving. The 364,336-square-foot building was developed in the 1980s. “We believe these renovations go a long way toward repositioning Tower 909 as one of the top office buildings in this submarket,” said Kim Brooks, principal of Transwestern, which manages and leases the property.