St. Louis and Lecavalier, holdovers from the Lightning's previous playoff squad four years ago, also led Tampa to the Stanley Cup title in 2004.
The Lightning, who won 46 games and had 103 points in the regular season, open an Eastern Conference first-round series Wednesday night at Pittsburgh.
"We've earned our way back to this," St. Louis said on Monday. "It's a longtime coming. I think we're ready."
Since beating Calgary in seven games for the championship seven years ago, Tampa Bay hasn't won a playoff series and missed out on the postseason each of the previous three seasons.
The Lightning ended the regular season by winning seven of eight. Also, St. Louis and Lecavalier also were effective when playing on the same line over the season's final weeks.
"I feel we're back to where we once were," St. Louis said. "I feel like we're really on the same page with our game. Both in a happy place, mentally. I think the last couple years we'd go back on the same line, I don't think we performed like we have the last two weeks together."
Lecavalier had to face several distractions over the past two years, including speculation that he might get traded.
Hall of Famer Steve Yzerman, hired as the general manager by new owner Jeff Vinik, immediately informed Lecavalier that he would not be dealt.
"The last two years have been tough ... like a roller coaster," Lecavalier said. "Not knowing what was going to happen. From the last two years to now, it's definitely night and day."
St. Louis has seen the off-ice stability assisting in Lecavalier's play.
"Let's not sugarcoat it here, Vinny had a couple tough years here with everything that's gone on," St. Louis said. "He's battled through the last couple years and he's earned where he is right now."