The Swede's side kicked off their double-header against the Olympic champions in Jackonsville with a 4-1 defeat on Saturday.
Signeul is now preparing for the second meeting in Nashville on Wednesday and said: "It takes time to get to the level that USA are at. We can already see that the coming generation is fitter and can compete on a more physical level with teams like this, but we need to keep working hard.
"You go into every game with the attitude that you want to win, but for these two matches we also wanted everyone to set individual targets that can be benchmarked against the best players in the world.
"It's also about providing motivation. When you are back at home, when it's wet and cold and you need to get up for training you need to think about why you are doing it.
"If you can think back to experiences like this and say, 'I want to be up there as well. Even if it is difficult today I know what I am aiming for. I want to reach the top of the game and I want more experiences like this, playing in front of 18,000 spectators in an amazing atmosphere'."
Signeul said: "It is good that we have a second match. We have time for some bonding and team-building but we can immediately work on a few things."