I am in the process of buying a jeep Laredo which seems to have condensation inside the headlamp glassis it possible to clean this/replace the glass/or is it best to buy a new pair

Condensation is deemed to happen if ambient temperature is lower than inside the headlamp and humidity inside of headlight is too high.
From a headlight design perspective, you cannot lower ambient temperature. Not much can be done with temp inside headlight either. However, humidity levels on the inside can be reduced. Most designs usually have 2 or 3 air vents to keep humidity below condensation threshold levels.
This might sound complicated, but the phenonomen is exactly the same as windows in a winter home and humdity levels inside. Too much showering, and bathroom window fogs up. Venting will reduce condensation.

You might wonder why headlamps are not designed to be 100% air tight, so that no humidity enters? Well, that would be in an ideal world with no heat losses in bulbs. As the headlights goes through continous warm-cold-warm-cold cycles as you turn light on and off, the air and plastic will expand and retract. This creates pressure changes, which will move a slight amount of air in and out. So instead of forcing the air to be inside, air is moved through controllable passages, so that minimum of road dirt will enter.

If condensation disappears within a week. Moisture can have been sucked up in high pressure wash. This should normally dissapate within a week by itself.

If condensation amount stays constant, then there is crack(s) in headlight that lets in water. This can be siliconed, depending where the crack is, or a replacement headlight should be considered.

If it is a sealed beam ---buy a new pair ---if it is the globe type thheat of the globe should dry it out

Interesting about the heat/pressure.

I wonder if the engineers ever considered a small rubber diaphram... seems like that would work.... like a ballon almost...

just a thought lol