Seneca Gaming Corp. is pouring money back into its three casinos, adding more slots and tables as it readies to meet any new competition.

When New York voters in November approved seven new casinos around the state, it raised the ante for existing gaming halls.

The Senecas have spent $26 million on a complete makeover of the main gaming floor at their flagship casino in Niagara Falls, which has been open for 11 years.

Due for completion in the next month, the layout of the slot machines and table games has been changed, and many of the 4,000 slots were replaced. The central bar and bandstand, called Club 101, has been removed and replaced with a new “feature bar,” called Stir, in a corner of the 2-acre gaming floor.

“You have to enhance the property. It’s a continuous undertaking. You can’t build something and just leave it,” said Kevin W. Seneca, chairman of the corporation’s board. “What would Disneyland look like if they built it and just left it?”

The corporation, owned by the Seneca Nation of Indians, is a significant player in the local economy. It employs more than 4,000 people at its three casinos, two hotels and a golf course, with a $121 million annual payroll.

“The nation has more than $1 billion invested in its gaming and hotel facilities,” said Cathy Walker, Seneca Gaming’s president and CEO.

Much of the investment was initiated before the November vote that could bring casinos to near Binghamton, the Catskills, the Mid-Hudson Valley and Saratoga Springs.

All the 604 rooms in the hotel behind the Niagara Falls casino were redone in 2012, and a second hotel tower opened in Salamanca at the end of 2012, bringing the room total to 413. The expanded Seneca Buffalo Creek Casino opened in August.

The Niagara Falls casino had an estimated 10 million visitors in 2013, while the Salamanca site claimed an estimated 3 million.

The Buffalo location is projecting 3 million players a year, though actual numbers have yet to be released.

Golfers played 22,356 rounds at the Hickory Stick Golf Course in Lewiston in 2013, another Seneca Gaming property. Golf Magazine listed Hickory Stick at No. 11 on its list of the best public courses in New York during 2013, while GolfWeek rated it the 25th best casino course in the nation.

Walker said even something as basic as slot machine themes can’t be allowed to get old.

“ ‘Sex and the City’ was popular last year. Well, this year, it’s ‘NCIS,’ ” she said. “That’s the kind of thing that goes on on the manufacturing side.”

The Senecas are hoping to lure more Canadians to their Western New York properties, despite the fact that Canadians have several home-grown casino choices.

Walker said Canadians already make up “a significant amount” of the customers at Seneca Niagara, though she wouldn’t be specific.

“Toronto and Mississauga, that’s our market,” Seneca said. “That one-hour travel time, be it across the border or down south – we look all the time at what we can do to increase that share, while trying to increase the two-, three-, four-hour drive time, which would put it past Cleveland, Columbus, that area. How do we give them an experience they can’t get anywhere else?”

The wider marketing radius is crucial to the success of Seneca Allegany Casino, Walker said, because it’s located in the sparsely populated Southern Tier.

She said the presence of ski resorts and state parks nearby helps bring in customers.

Walker said the urban setting for Buffalo Creek limits physical growth possibilities, but the Senecas have partnered with such local food icons as Charlie the Butcher, Pearl Street Brewery and Duff’s wings, selling their goods in the Buffalo casino’s restaurants.

“It’s another way to build that branding of ‘This is Buffalo,’ ” Walker said.

“When you’re trying to have them stay for two, three, four hours, they have to have something that’s convenient, something that has good-quality food that they like and can enjoy on their visit.”