The Championship side netted a combined figure of more than £24m for winger Jarvis and striker Fletcher, sold to West Ham United and Sunderland respectively.
"We will invest the money back into the team," Moxey told the Express & Star. "We've got a number of other players in the pipeline which we're hoping to complete. We're a little exposed because we've sold two of our best players so we have others to bring in."
The club picked up Austrian defender Georg Margreitter for £2m earlier today and are also thought to be chasing FC Copenhagen's Christian Bolanos (£3m) and Man United's Robbie Brady (£1.2m), both wingers.