If the Knicks are to make the leap from a second-round playoff team to a legitimate title contender to Miami’s throne next season, combo guard Iman Shumpert will have to make a leap, too. Shumpert, whom the Knicks drafted at No. 17 in 2011 with their last first-round pick, is facing his first full 82-game schedule in his third season as a pro. He potentially could be needed as the Knicks’ secondary scorer to Carmelo Anthony if free agent J.R. Smith, who opted out of his contract yesterday, gets blown away on the open market and leaves. “I think I can be [a secondary scorer],’’ said Shumpert, whose four 3-pointers in the third quarter of Game 6 of the Eastern Conference semifinals in Indiana nearly saved the season. “I’ve always accepted all challenges. I’d take that as another challenge.’’ With all of the explosiveness possessed by Shumpert, who was named First-Team All-Rookie in 2012, it was a surprise the U.S. Olympic Team didn’t invite him to a 25-man developmental minicamp in late July for young American prodigies in Las Vegas. Shumpert’s ACL tear that delayed his season debut until January may have put him off the radar. One Team USA source said his position wasn’t a need. “I wasn’t thinking about it,’’ said Shumpert at his basketball camp in White Plains. “I took the loss in the playoffs pretty hard. There’s always next year. [Not getting invited] was a little bit of salt [in the wound]. I didn’t think it was big deal until everyone started tweeting me. I would’ve loved to go, loved to compete, loved to help.’’ Shumpert said on the Knicks’ breakup day he would compete in the summer league in Las Vegas for the first time. When he was a rookie, summer league was cancelled during the lockout. Last summer, Shumpert was in a left knee brace, rehabbing following surgery. “I want to come out and work on my stuff,’’ Shumpert said. “It was tough losing in the playoffs, but I felt I built a foundation. I’ve sat out six months. I’m done sitting out.’’ Shumpert was rusty upon his return and didn’t start rounding into form as a two-way menace until late March. With Jason Kidd’s retirement, he could see more time at point guard. “I’m working to get my handle tighter,’’ Shumpert said. “And make decisions earlier. Instead of coming out there guessing, I have to have a plan and more consistency.’’