Dunn, 30 in December, made just 17 appearances during an injury-interrupted 2008/09 campaign in which he was sidelined for four months early on.
He has featured in Rovers' last two games, playing his first full 90 minutes since January 2008 in Saturday's goalless draw at home to West Ham.
With central midfield patrolled by the likes of the defensively-minded Steven Nzonzi, Vince Grella, Keith Andrews and Steven Reid, Dunn offers some much-needed creativity.
However, Allardyce knows if the player is to rediscover his best form he needs to be playing in regular long spells.
"You have to try to get Dunn fit for 25-30 games," said the Rovers boss.
"That has been the unfortunate situation for David over the last couple of years.
"I didn't expect I would leave him on for 90 minutes against West Ham with him having played 60 minutes at Gillingham (in a Carling Cup tie four days previously).
"But I was glad to say I thought David got better as the game went on. He was popping up with the ball more and more."
Allardyce hopes to take advantage of the current international break to get more of his injured players fit and his squad back up to full strength.
The likes of Reid and Brett Emerton are just returning to action after long-term knee injuries while on-loan Chelsea forward Franco di Santo and striker Benni McCarthy currently have hamstring and ankle problems respectively.
Former Real Madrid defender Michel Salgado is also working his way up to match fitness after his transfer a fortnight ago.
Croatia striker Nikola Kalinic scored for the reserves in the 4-1 victory over local rivals Burnley last night but the 21-year-old's Blackburn career is just three matches old and Allardyce needs to get his other attacking players back after scoring one goal in three Barclays Premier League games.
"The people who are injured won't be travelling with their international teams so it gives us two weeks to get them up to speed," said the Rovers boss.
"Reid and Emerton are very experienced players for Blackburn and we have to get them back as soon as we can, hopefully by the time the international break is over.
"That will add to the squad, Michel will be ready to go by then, Pascal Chimbonda will have settled in even more and we may have Franco back.
"Hopefully when we come back we have got everyone fit and ready to go again.
"Then we can look at the squad as a whole and be a much better force from the end of the international break in terms of what we have got to select from at the moment."
France Under-21 midfielder Nzonzi has played in all four matches this season and has settled in well having moved from Ligue 2 side Amiens.
Allardyce's signing of the little-known player in June is already looking like a masterstroke, although Nzonzi admits he still has plenty to learn.
"It has gone off quite smoothly so far. At first, I had some difficulties to play so many matches in a row, because it is much faster," he told L'Equipe.
"You also have to match the physical impact, being present in the challenges.
"I have to become stronger and play quickly to the attack."