What made Romulan Ale Romulan? That it was made from a Romulan recipe, or that it was made on Romulus? After the destruction of Romulus, was any new Romulan Ale produced?
The official Star Trek web site maintains a brief, but very informative database entry on Romulan ale, known in the Romulan tongue as "kali-fal":
An infamous blue alchoholic beverage with a powerful kick, the drink has been banned in the United Federation of Planets since before 2285 and is still not a commonly-known commodity.
It was unavailable even for replication aboard the Enterprise-D in 2366, to defecting Romulan Admiral Jarok's dismay.
A shipment hijacked by Fallit Kot around 2362 landed him eight years in a Romulan labor camp after middleman Quark turned on him.
The article implies that true Romulan ale is scarce outside Romulan territories and is manufactured almost exclusively within the Romulan Empire, as an associate of Quark had to obtain it by hijacking a shipment from Romulan space.
Rules on DS9 are, of course, more lax than on purely Starfleet installations, and we know from "In the Pale Moonlight" that Romulan ale is available for replication on the station, at least for Senator Vreenak's visit if not earlier. However, the conversation between Vreenak and Sisko suggests that an aficionado of the drink would know the difference between the authentic Romulan-sourced product and replicated stuff:
VREENAK: A fair approximation. Somewhat lacking in aroma. Real kali-fal should forcibly open one's sinuses well before the first sip.
Finally, as for Romulan ale after the destruction of Romulus at the hands of the Hobus supernova, I'm afraid that recorded Star Trek history in the Prime Timeline ends after the Countdown comic book series, an accompaniment to the Star Trek (2009) reboot. The Countdown series, while dealing with the destruction of Romulus, fails to address the fate of production of the galaxy's favourite loosen-up-the-mood beverage.