Villa's 1-1 home draw with Tottenham on Sunday lifted them three points clear of Bolton and there would have to be an unlikely 17-goal swing on the final day for the midlands club to go down.
McLeish can point to a shortage of experience, a lengthy injury list, blooding too many youngsters and having to drastically reduce the wage bill as mitigating circumstances.
But the former Birmingham boss will still expect better during 2012/13.
He said: "We are assessing next season. It's all been ongoing. We've been assessing it every single week. We've got to start putting a plan of action in place.
"Listen, I have taken a lot of weight on my shoulders this season. I was happy to take pressure off the players.
"I am not going to again next season though. They had better get their finger out.
"We've had to be in a bit of a dogfight all season.
"Our early-season form wasn't too bad but, since the New Year, we've had problems to contend with injury-wise.
"To lose two of your most experienced players (Darren Bent and Richard Dunne) for such a long time will hurt any team."
McLeish has struggled to win over the Villa fans and there were again calls for his sacking in some quarters after Sunday's clash with Harry Redknapp's side.
But he said: "I think the Villa fans in general have been excellent. I met some nice people at the end-of-season dinner the other night.
"I felt the guys I met were genuine, they knew what I was working with. If I get that kind of understanding, then great."
McLeish added: "I would certainly look to be strengthening the squad for next season.
"This season we have taken the plunge into the reduction of wages. It's hopefully helped the finances a little bit.
"It has put us through the mill, no doubt about it, but we're planning and we can rise. At clubs I've worked with before, with proper planning, we've done well.
"If I can go through that this season, I will have to have a crack at the big time and try and enhance the quality of the squad.
"At the end of the day, it's down to the players."
McLeish received backing from Redknapp who said: "Alex has had a hard season here. The league is getting tougher, everyone is having a go.
"They need to have a bit of a go next year to try and get back to where they were to give Alex a chance otherwise it's a hard.
"Villa keep producing good young players and have got a fantastic youth set-up.
"But Alex needs one or two players to strengthen his team."
Former Villa midfielder Paul Merson claimed: "If Sir Alex Ferguson, Jose Mourinho or Arsene Wenger were in charge, Villa would still be where they are."
Redknapp is braced for a thrilling finale to the campaign in the battle for a Champions League spot.
Tottenham will secure fourth place if they defeat Fulham at White Hart Lane but have to hope Arsenal slip up at West Brom if they are to finish third.
He said: "We know the importance of next weekend's game. If we win, we can't finish any lower than fourth and that is what we have to make sure we do.
"In an ideal world we would have won at Villa and put finishing third into our own hands but you can't always have what is ideal.
"It is all to play for. There are so many different permutations that could happen now."
Redknapp admits he has a problem at left-back after Danny Rose's red card against Villa means left him suspended for the return of former Spurs boss Martin Jol's side.
He said: "It leaves us with a problem at left back now because Benoit [Assou-Ekotto], my regular left-back, has had an operation on his shoulder.
"It was a good opportunity for Danny to establish himself. We haven't really got a left-back for next weekend."