Sam Allardyce is hoping to delve into the transfer market this summer as he looks for West Ham to kick on next season.
The Hammers are 10th on their top-flight return with three games remaining.
"To improve we just need to add better players, it's a simple as that," Allardyce said on West Ham's official website.
"If we get better players, then we improve. If we can do that, then we get better and we become an established Barclays Premier League side."
Allardyce is content with his side's position in the table and added: "At the moment, we are far better than where we expected to be.
"We didn't expect to be almost safe with four games to go. I think we'll be okay with 42 points so we're way ahead of what we expected.
"As I say, we need to get a few more goals to get the points. We'll address that in the summer and hopefully we'll find some better players to improve the squad.
"Before that we've three very important games, two at home and one away so we'll try to pick up as many points as we can."
Pompey's traumatic campaign, during which they have used more than 50 players and almost went bust before the PST completed their takeover earlier this month, ended with a 3-2 defeat at Shrewsbury.
Whittingham has already said he wants to keep the bulk of his current squad in a bid to bounce straight back from relegation to League Two.
"There's a lot going on in people's heads at the moment with talk about who's staying and who's going," he said.
"A lot of people have been watching our players closely, but we'll try to keep as many of them as we can.
"It's been an unbelievable season. I don't think any club has experienced anything like it in the past and I hope no-one does in the future.
"Football is a rollercoaster ride and there are always ups and downs. There was a big peak last Saturday, although we've now come down a bit."
