Hi,
To get good range using a regular IR LED and IR sensor you can modulate the IR LED at some fixed frequency and use a receiver with a front end filter to detect the light. It sounds like you are already modulating the IR LED, so all you need to do is build a filter. One of the problems is that the ambient light is usually also changing in intensity due to the nature of bulbs and other types of lighting. The light interferes with the IR light because there is some IR light from them too and also the detector might be sensitive to IR and other light too.
The filter can be a bandpass, but because most of the 'noise' light is at a very low frequency you can get away with a high pass filter. Say 5th order or something like that and you can even get away with a passive filter if you provide amplification after it. This can extend the usable range to several meters with standard components and drive power.