Barcelona coach Xavi Hernandez said his team had a "a huge amount" to change next season after Real Madrid claimed their LaLiga crown on Saturday.
Los Blancos beat Cadiz 3-0 and after Barcelona were hammered 4-2 by Girona, sealed their title triumph with four games to spare.
Barcelona, who won the league last season, are third after the defeat and collapsed in the second half in a pulsating derby clash.
"We have to continue with the project, the first few minutes were brilliant," Xavi told DAZN after the Girona defeat.
"We will keep fighting and next season we have to change a huge amount of things."
Barcelona twice lost the lead against Girona, who netted two goals in two minutes in the second half to go from 2-1 down to 3-2 up.
"We lost control of the game because of flagrant errors that cannot happen at this level, we've talked about it but it keeps happening," added Xavi.
"It's a shame, we sink with any negative situation... like this, it's impossible to compete."
Barcelona lost both matches against Girona by the same scoreline and also were defeated by Real Madrid in the two LaLiga Clasicos.
"We gave the game away, it's a summary of the season," added Xavi.