Shares of Bedford’s iRobot Corp. rose after the company said it is beefing up its line of vacuum-cleaning robots with a $699.99 model called the iRobot Roomba 790. The new model includes a redesigned faceplate, room-to-room navigation features, and a wireless command center. The company makes robots for use by consumers and others designed for uses by the military and law enforcement agencies. These robots can perform such tasks as scoping out battlefields.