Kenny Jackett stressed Pompey must use the summer to build on this season’s fourth-place finish.
The Blues fell just short in their bid to bring Championship football back to Fratton Park.
Jackett’s men suffered play-off semi-final defeat to Sunderland, meaning they’ll spend a third successive campaign in League One.
After the failed promotion push, Jackett revealed he held talks with chairman Michael Eisner and the Pompey board on how to move forward heading into the 2019-20 season.
The Blues boss felt there were positives to take from this term – pinpointing his side’s Checkatrade Trophy triumph and run to the FA Cup fourth round.
But Jackett stressed Pompey can ill afford to lose any ground on their rivals and progress further next campaign.
He said: ‘Obviously, there were some opinions then the majority was about what we do going forward to make sure we don’t fall away and keep strong. Ultimately, that is all our aim.
‘Then we’re talking through the possibilities of how we build the best squad we can this summer.
‘Yes (talks were positive), although we are disappointed not to have gone up, of course.
‘Looking at it myself, not taking the lead or winning any of the last five games.
‘As a season overall, we gave it a good go and had a run in both cup competitions.
‘But it’s really important we build on it and don’t fall away so we can compete again.
‘That is a big thing and it’s about how we work in our run-up to pre-season and the transfer window.’