optical design

We manufacture a gun containing an IR diode, one of the barrels emits a 940nm narrow beam for a few milliseconds at a modulation of 38KHz when fired. a target containing retroreflective corner cube tape reflects the signal back to the other barrel of the gun to register a "hit". We wish to increase the range of this gun from 20M to 60M if possible. No lenses are currently used. We've tried lenses, but we're not optical engineers, so we've had little success. advise on costs if you can help.