A lot of the flavor of fruit comes from the sweetness, which ferments out. If you keg, you can backsweeten and it will bring out more of the fruit flavors. You can also mash hotter to leave you with a higher OG which will help some. you could also add a little lactose, or other unfermentable sweetner. You don't want enough to make the beer sweet, but need something to back up the fruit essence.