Over the past few years, the market calls made by bullish strategist Tom Lee have proven prescient. Now, he predicts that 2015 will be an even better year for the market than 2014.

"We remain bullish and expect the S&P 500 to reach 2,325 by YE 2015," he wrote in a Thursday morning note to clients.

With the S&P hitting 2,050 on Thursday, a close of 2,325 would represent a rally of more than 13 percent from current levels. That would easily best this year's 10.6 percent rally.

So how does Lee, the current head of research at Fundstrat Global Advisors and former equity strategist at JPMorgan, reach that target?

"What we're picturing is that earnings growth is around 7 percent or better, and we see the P/E expand," meaning that investors will pay more for each dollar of earnings even as earnings rise, he explained Thursday on CNBC's "Futures Now."

The reason this is a surprising take is that market valuations have already risen considerably, such that the S&P's forward price-earnings ratio is now a bit above historical averages. But that doesn't worry Lee.

"I know people are going to say, 'Hey, the P/E expansion's over, because we're already six years in and the market's at 16 times forward [earnings].' The reality is, if you look at every bull market that's lasted at least four years P/Es expand more than one turn a year until the bull market peaks," he said. "Hey, the market feels expensive, but the P/Es' going to keep going up until there's a recession."

Read More Stock rally could depend on oil pressure

And Lee isn't concerned about the fact that the Federal Reserve is looking to raise short-term rate targets in 2015.

"When the Fed begins to tighten and it's really essentially a confirmation of a reflation signal, the stock market actually takes those quite well," he said. "There's six or seven episodes in the last 50 years when the Fed tightening has led to the markets actually rallying, and we think that's going to be the case [this year] as well."

Known as one of Wall Street's biggest bulls, Lee predicted in 2013 that the S&P 500 would rise to 2,075 by the end of 2014—an out-of-consensus call that now looks pretty accurate. Similarly, he was the biggest bull on the Street in 2013, a year in which even his calls proved not bullish enough.

Lee says that with so many people expecting a mild year of market gains, he's again looking the other way for a different result.

"A lot of people are thinking next year's a low-return year because we've got disinflation, we've got lower oil and the problems in Europe and China," Lee observed. "And you know what? That's what consensus is, it's either going to be better or worse, and we think it's going to be better."

Watch "Futures Now" Tuesdays and Thursdays at 1 p.m. ET exclusively on FuturesNow.CNBC.com!