Reducing IR proximity sensor module power consumption
Remove the two LEDs (over by the connector in your picture.)  Lighting them uses current.  Not much, but you don't really need them.
Increase the resistor in series with the IR emitter LED.

(2.) will probably have the most effect.  It will probably also reduce the detection range.
Use a camera to find out which of the two LED like things is the IR emitter (on the right end of your picture.)
I expect it will be the clear one.
In any case, you can &quot;see&quot; IR with most digital cameras (smartphone cameras, photo cameras, webcams, etc.)  Look at your sensor through the viewfinder of your camera and see which is lit up.
Trace the connections to that part.  You will find a resistor in series with it.
I expect that resistor will be some few hundred ohms.
Replace it with a larger value resistor.  A value of two or three times the original should be a good starting place.
Try your sensor out.  If it works reliably, run it for a couple of days and see how your battery holds up.
Try a larger value to get a longer run time, but keep in mind that a larger resistor will shorten the detection distance and at somd point the detector will not work anymore.