infrared – Extend PIR range by adding a lens?

I bought this solar powered wifi camera. I stuck it in a tree above my front gate, hoping to automatically trigger to record vehicles and people in front of it. The footage uploads to the web, via my wifi network.

Whilst the video quality is fine and uploading works, the PIR detection range is inadequate. They claim 10 meters, but I reckon its less than that.

Would it be straightforward to extend the PIR range to say 25 or 30 meters by sticking a lens in front of what’s there already (a fresnel lense)?

I understand the extra lens would need to be transparent to infrared.