The explosion destroyed a US$200 million Israeli satellite and heavily damaged the launch pad.
SpaceX is also modifying the rocket's engines to increase performance and resolve potential safety concerns, said Shotwell.
Nasa has hired SpaceX to taxi astronauts to and from the International Space Station starting in late 2018.
SpaceX is one of two companies certified to fly military and national security satellites for the Air Force, the other being United Launch Alliance, a partnership of Boeing Co and Lockheed Martin Corp.
The company has a backlog of more than 70 missions, worth more than US$10 billion. It has successfully flown 27 out of 29 times since the Falcon 9's debut in 2010.
The company flew eight missions in 2016 before the launch pad accident in September grounded the fleet.
The rocket returned to flight last month, flying from a second launch site in California, which is only used for satellites heading into polar or high inclination orbits. A fourth launch site in Texas is under construction.
- AAP