The St Mary's Stadium outfit finished 14th in the Premier League in the last campaign in their first term back in England's top flight.
Manager Mauricio Pochettino, who succeeded Nigel Adkins in January, has already brought in Croatian defender Dejan Lovren in order to strengthen the squad for the next season.
And ahead of what can often prove a difficult follow-up in the Premier League, striker Lambert thinks it would be good to see some further signings.
"We're more than confident in the team we've got now but hopefully the gaffer is going to bring in a few to improve us as well," Lambert told Southampton's official website.
"It's ideal to get people in at this stage. As a player, you can't underestimate how important that is. Thankfully we've got a good lad and a good defender in, and hopefully we can get a couple more in.
"Even if we don't, I still think we've got a very good squad with very good people. We've all had a season in the Premier League, so I think we'll be even better next season."
Southampton had a difficult start to last season, facing Manchester City, Manchester United and Arsenal among their first four games.
They lost narrowly 3-2 to both Manchester clubs before being thrashed 6-1 by Arsenal but this season they will face West Bromwich Albion, Sunderland, Norwich City and West Ham United in their openers.
It is a preferable fixture list, however, Lambert is warning against complacency, as he said: "If you turn up five per cent away from your best, you'll get beaten by any team - and battered sometimes as well.
"It's a hard, hard league but we've got to be confident in ourselves."