to make this harder, i would have alot more percussive elements, i would add delay to alot of the percussion, i would have harder sounding hats, these are a little too 808 sounding.
Also try adding a few synths in to the mix, they dont have to be screaming synths, alot of tracks have synth lines in there, but you cant really hear them, they just help to add some energy.
Finally, i would add a nice sub bass line