Going by your description, you will be very happy to get the red dot back in some shape / intensity !And what is the purpose ? Just to know if "that thing" is there ?

Unless the reflective index of the target surface is defined I doubt if you can plan a method to pick the bounce back image with visible wavelengths.

If you have no control over the target surface then laser may not be a viable option. Not sure about the budget of this project - but still some solutions would be :

1. Short range SONAR.
2. Modulated IR transmitters and matched receivers.
3. A CCD camera and image matching ;-)

Raghu