Lita was shipped out on loan to Championship club Charlton last week after becoming frustrated with a lack of first-team opportunities at the Madejski Stadium, and Long is determined to ensure that there will be no place for him in the side after his spell at The Valley has ended.
"Leroy is a great player and scores goals," he said. "But if you are not playing, you can lose that instinct for scoring.
"I wish him well and when that loan spell ends, he could come back, so I have to perform every week.
"You need competition in the squad and I need to try and keep him out of the team."
Long is confident that there is more than enough quality within the squad to maintain their top-flight status.
"I think we can finish in the top 10," he said ambitiously. "We are definitely good enough.
"We need a few more wins to get clear of the dreaded relegation zone first though.
"Six points in two games, you can't complain about that. The confidence is back and the pressure is not on our backs.
"I think we are good enough to stay up. I have been saying that since we were 18th."