Improve their soccer abilities in a perspective ot the future and not to the present.
Winning or losing is important, but above of all, is more important to grow as a player, cause with 13 years, they have more important thing to worry about than lose or win a game.
Although, is important to teach them the difference of a good or a bad result, and teach them always looking for victory.
you said "we have more losses now than we have had in the last 3 years", and you give that result, a huge importance, that is probably giving them a big responsability they arent't capable of passing by.
Let them enjoy the game, cause when they get to pro or a hig level, they will be force to win
