Is there a way to remove condensation and clean inside a double pane window?
No. You're limited by what you can do from the outside, and obviously that's not much. 

Energy efficiency is only slightly reduced in such cases, as airflow into and out of the compartment between panes is minimal, but the aesthetic problem will only get worse. 

Chances are you can replace just the sash, which might cost about half of what a new window would and doesn't require carpentry work aside from a little hardware swap.