Bristol Rovers plan to make early moves in the transfer market to strengthen the side for next season.

Director of football Lennie Lawrence told supporters at the club's annual meeting last night that the Pirates needed to be "sharp, quick, ruthless – and lucky" with their recruitment as they reshape their squad for the next campaign.

And coach Paul Trollope confirmed that the club would be primarily looking to bolster defensive and midfield areas as they bid to build a team capable of challenging for a top six place.

Lawrence said: "We have made progress in the last two seasons in League One – next season we have to do it again and kick on."

But he warned that trying to make the play-offs next term would "present a challenge" because of the likely strength of the division.

He said: "There won't be teams coming up from League Two this time with the spending power of MK Dons or Peterborough.

"But there will be clubs coming down like Southampton, Charlton and Norwich who can attract gates of around 20,000 and will still have a number of Championship players – as well as strong teams who won't be going up through the play-offs this year.

"I think Bristol Rovers can sustain Championship football in the future and we will get there in the end. But it will need patience and tolerance – and key players to stay injury-free for virtually the whole season."

Trollope said one of the main priorities last summer was to improve the side's striking power – and the Pirates have been boosted by Rickie Lambert's 28 goals this term, while Darryl Duffy and Jo Kuffour have both reached double figures.

"But we do have issues in defence and midfield that need addressing," he said. "There will be strengthening. We have identified areas and individuals who can help us progress."

Rovers are likely to announce their decision on the futures of four out-of-contract players – Craig Hinton, Craig Disley, Joe Jacobson and Ryan Green – next week.

But Lawrence confirmed Richard Walker, who has spent the season on loan at Shrewsbury, would not be getting a new deal. The futures of Andy Williams and Lewis Haldane – who have been at Hereford and Oxford respectively – are also uncertain.

Lawrence said Oxford had made an inquiry about making Haldane's stay permanent while no decision had been made on whether Williams would return to Hereford for another loan spell, go to another club or return to Rovers.

The club will continue to use the Army base at Colerne as their training base at the start of next season, but hope to move to the South Bristol Sports Centre in Knowle in September or October once drainage problems are resolved.

Lawrence said Rovers hoped to play a high-profile pre-season friendly against a Spanish club at the Memorial Stadium as part of their build-up for the new campaign.

They have already agreed games at Torquay (July 18), Cheltenham (July 21) and Hereford (date to be confirmed) and were also hoping to arrange a match against Plymouth Argyle.

Chairman Nick Higgs said the club was pushing ahead with plans to redevelop the Memorial Stadium and that "things are moving in the right direction."

He said tenants Bristol Rugby had been offered a 35-year lease at the ground. "To all intents and purposes they have agreed, but we are just waiting for them to sign it," he said.

But if they did decide to go elsewhere, it would not mean putting the stadium redevelopment on hold.