light is attenuated as inverse-square law, so even with a lens the signal strength will very rapidly fall off with distance. If your lens system gives you 100 times the brightness compared to no lens, that's only a ten-fold increase in range, and then only if the focus and aim are set up just right...
I'd use a red LED for now, so you can see where the light is focussed, and set things up. Then go back to IR diode and you will have to readjust the focus a little due to chromatic aberation.
More sensitivity can be got by adding a lens to the revceiver too.