Two defeats in Barcelona's last three league fixtures, at Real Sociedad and Real Valladolid respectively, have seen the Catalan giants drop to third in La Liga.
Gerardo Martino's side are four points adrift of leaders Real Madrid, but have one foot in the quarter-finals of the UEFA Champions League after winning 2-0 at Manchester City in the first leg of their last 16 tie.
Barca are also in the Copa del Rey final, where they will meet Real Madrid, and Alexis is confident they can claim a treble.
"We are in the fight for all the titles," he said.
"I am hungry to win and so are all my team mates. We want to win everything, the league, Champions League and the Copa del Rey.
"I don't know anyone in the squad who doesn't want that.
"We are all part of Barca and we have the same aim. The league isn't lost, just as when we were on the top people were wrong to say we had it won."
Alexis has urged his team-mates to move on quickly from their shock loss to strugglers Real Valladolid.
City visit Barcelona on Wednesday for the second leg of their Champions League clash and the Chilean knows they must be at their best.
"We have to put the loss against Valladolid behind us now and not feel sorry for ourselves," he added.
"Manchester City might have lost the first leg, but every team is always really fired up for a game against Barca."
Alexis has scored 18 goals for Barcelona this season in 39 appearances.
