Manager Antonio Conte says Chelsea has to "improve in terms of numbers and quality" during the summer transfer window.
The Italian was delighted with how the season unfolded with very few players suffering injuries during the campaign.
But he will need depth if the Blues are to be competitive in both the English Premier League and Champions League next season.
"Now the most important thing is to give a correct evaluation of our season because for me it was incredible," Conte said after Sunday's defeat.
"Every single player performed at 120 or 130 per cent in every game. We didn't have many injuries.
"It's very important to understand this. Our season was incredible because every player worked very hard and next season for sure we must pay great attention to understand we have to improve in terms of numbers and quality.
"That's very important and we must be very cold when we analyse the situation and understand this season we did something great.
"This season has been a great one for us, to win the league with 30 victories, and reach the final of the FA Cup is incredible.
"My players must keep in their mind our fantastic season and also this final, because you have to reach this point to play the final. We must be proud."
