The O's were finally assured of safety in League One on Saturday despite losing at Hartlepool thanks to results elsewhere.
"We'll review the season and that starts almost immediately," said Slade.
"We'll sit down, we won't leave anything to chance, we'll turn over every stone and we'll look to improve and build for next season.
"As normal at the end of the season there will be a lot of players available so we need to look at that element as well - what we can bring into the club, what we can't, what budget we have, there's so many questions we have to answer.
"We want to answer them quickly, but we'll take our time so we don't make any mistakes and we have a clear view, so we can start again in a positive manner."