Gillette is facing a new threat from one of its oldest rivals

In the words of Donald Trump, paraphrasing his father: "When you're on top, you've got a lot of people gunning for you."

Razor giant Gillette, fresh off of new initiatives launched to fend off startup competitors like Harry's and Dollar Shave Club, is now facing increasing competition from one of its oldest adversaries.

Schick, a brand of razors manufactured by Edgewell Personal Care, is now sticking it to the market leader where it hurts.

One of Gillette's biggest advantages is its ecosystem. The brand figures that since you've already purchased the handle and other accessories, you may as well keep purchasing the refill blades that fit it.

Schick knows that, so it's created a new line of razor refills, called the Hydro Connect, that fit Gillette's Fusion or Mach 3 razors but cost less than Gillette's refills.

"Men are creatures of habit, and anything we can do to lower the barrier of entry to try our product will be helpful," Patrick Kane, who handles Edgewell's shave-products-for-men business, told the Wall Street Journal.

Schick is also launching a shave plan that allows you to choose which blades you want - a five- or three-bladed head that connects to Schick razors, or the Connect. It also allows you to pick how many refills you want each time, as well your preferred time frame, which can be as infrequent as every nine months.

Each cartridge runs from $1.78 to $3.33, a price based on the blade and how many are in the shipment. You can sign up for the plan at Schickhydro.com.

Edgewell is one of the last big razor players to land online in an increasingly crowded space. Earlier this year, Gillette made a big splash with its Gillette On-Demand direct-to-consumer online store, a reimagining of the shave subscription club it has had for years.

Schick claims roughly 15% of the US razor market for men, according to Euromonitor. That number has fallen from 19% as recently as 2011. Gillette still has the lion's share with about 54% of the market, though that's down from 70% six years ago.

Much of the rest of the pie is split between Harry's and Dollar Shave Club, which have eaten away at both of the bigger players.