Barcelona is still in shock of what PSG did to them, and they might not be able to put themselves together to bring out the best in them. Real Madrid will be motivated the more in this match, because they will not want Barcelona to make them drop point. Their frontline is strong compare to Barcelona.
I know that Barcelona have picked form, and they might also want to let Madrid to know that they can win the game, if only they can outsmart Real Madrid strategy and take it as an advantage to win the match. I don't think that even if Barcelona play the best they can, that they will win the match, the highest that they can do is to draw the match and share points. Madrid is still the favorite to win because the match is taking place in their home.
Considering that Real will play Bayern on April 30, they will save their energy and play with the second squad in the game with Sociedad. In order to avoid any surprises, the most profitable thing is to increase your points advantage over second place. Therefore, I think that in the clasico Real will play strictly to win and taking into account the fact that Barcelona should also play to win (they have nothing to lose and they do not risk anything), I can suggest that it will be an open game and Real will win with a score of something like 3-1.