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 whufc.com.
"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."