Press [Ctrl] + D to drop a gun, then pick it up again. The current clip will be refilled.
Cheats
JASSICA16 = Enable Cheats
CTRL-F10 = Enable Immortality
F10 = Get more weapons, max out energy, and get all items
H = Hack mover (Hold down shift, then click and drag whatever)
~ = Turn cheats on and off
CTRL-V = Memory stats, version #, and other misc. stuff
CTRL-L = Shows current location
CRTL-Q = CD Transfer display toggle
F7 = Display grid over level
ALT-F7 = Display a different grid over level
F = Display object framework
Useful Command Line Parameters
-warp x (where x is a #) = Warp to level x
-skill x = Change default skill level to x (useful when using -warp)
-egg 250 = Weapons room cheat (must be used with -warp)