Closed for a few days for renovations as part of a nationwide rebranding, the Friendly’s restaurant on Arsenal Street reopened Thursday with a new decor and a revamped menu. The restaurant received fresh coats of paint, new seats, reorganized seating patterns, and more distinct ice cream counters, said a company representative. The Wilbraham-based chain has also revamped its menu to feature new dishes and to make improvements to classic offerings. Friendly’s employees will go through retraining and recertification exercises as part of the revitalization effort, and the company’s chief executive, John Maguire, recently told the Globe that he plans to offer tastier fare, faster service, and cleaner restaurants. The company filed for bankruptcy protection in 2011 and closed about 100 restaurants, including dozens of locations in Massachusetts. However, the Arsenal Street restaurant has remained open since 1983, officials said. To celebrate the renovations, the restaurant will be offering “Happy Ending” sundaes for $1 through Sept. 11, and will donate $1 to the Watertown Boys & Girls Club for every ice cream dessert sold through Wednesday, representatives said.