i am pretty sure most of the active players know this phenomenon: you waited the full 2 hours just to get 1 energy point (too much in my opinion). then you ride across the map to hit a castle you have scouted before. somewhere on the way another player challenges you, and no matter what you do, you are screwed.
my idea to make duels a little bit more worth it and to give an incentive to play good troops is quite simple:
in case you get challenged and you win, you should get the energy refunded. you still have to deal with lost troops and mana, but this would be a huge change.
i would not refund the energy in case you attack and win, since then whales could attack as often as they want.