Image: J.C. Penney.

Discount retailer J.C. Penney (NYSE:JCP) has gone through a tumultuous few years. Its attempt to revamp itself as a higher-end department store that wouldn't be so dependent on promotional discounting backfired. In response, J.C. Penney repositioned itself to try to recapture its lost customers, while still aiming to capitalize on some of the innovative ideas it implemented to reinvent itself and appeal to a broader audience.

With the stock up more than 30% so far in 2015, J.C. Penney investors want to know if shares could rise further from here. Let's look more closely at how J.C. Penney has fared and whether the second half of the year could bring even bigger gains for shareholders.

J.C. Penney's fundamentals
From a fundamental standpoint, the stock's performance doesn't necessarily connect perfectly with the results the company has posted lately. The stock has pushed higher despite the fact that J.C. Penney has struggled to return to profitability.

The retailer managed to achieve breakeven results on an adjusted-earnings basis for its fiscal fourth quarter ending in January. Even that came as something of a disappointment in light of hopes that the company would be profitable in the key holiday season. The winter and early spring season was even crueler, with an adjusted loss of $175 million, or $0.57 per share.

Yet for those willing to look at J.C. Penney from a longer-term perspective, it continues to make incremental progress. In its most recent quarter, J.C. Penney managed to increase its margins dramatically, having successfully boosted its private-label brand sales while efforts to cut overhead and administrative costs paid off in substantial gains in operating income. Even more encouraging was Penney's boosting its comparable-store sales guidance to the upper end of its previous range, with expectations now for 4% to 5% growth for the full fiscal year.

Where Penney's turnaround will come from
In particular, J.C. Penney has focused on a few key initiatives in its efforts to drive growth. Store-in-store boutiques were a keystone of the company's long-term strategy under former CEO Ron Johnson, and Penney's relationship with beauty-products specialist Sephora has gotten a number of customers into the retailer's doors who might otherwise have steered clear. Thanks to the Sephora shops, Penney has seen an increase in both the number of shoppers and their willingness to shop throughout the store and spend more.

Meanwhile, outside of its retail store network, J.C. Penney is embracing the online shopping experience as a way to generate more interest in its offerings. The company has noted that what it refers to as "omni-channel customers" shop two-and-a-half times more frequently than customers who only visit physical stores. J.C. Penney has finally come out with a mobile app and rolled out in-store pickup to facilitate delivery of items bought online and entice online shoppers to spend some time in Penney's stores.

Has Penney stock stalled?
Despite some exciting news from Penney throughout the year, nearly all of the stock's gains came in the first couple of weeks of 2015. The retailer defied initial expectations for poor holiday-quarter performance and announced same-store sales growth of almost 4% during the key November to December period, encouraging investors after the stock had fallen to its lowest level in decades.

One thing that has likely held back shares of J.C. Penney since then is the simple fact that the company has so far to go in order to regain its past level of success. During most of 2012 and 2013, same-store sales plunged at a pace that at times exceeded 30%. Even though Penney clawed back some of that lost ground in 2014, the magnitude of the comp gains was relatively small, never reaching double-digit percentages. Although investors have celebrated the idea that Penney might finally have hit bottom, the new normal for the retailer could well be a much smaller reach than the company used to enjoy.

J.C. Penney's strong performance so far in 2015 reflects optimism that better things might be in store for the retailer in the near future. For those expecting a full turnaround, though, it's still far too early to tell whether J.C. Penney can succeed in achieving all of its long-term goals.

Dan Caplinger has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.