Whether you want to learn how to work out, ride a bike or speak a new language, you will have to face repetition. Unless you’re a robot, you’ll need to get exposed to a new word or grammatical structure again, and again, and again.
In other words, there’s no other way than drilling.
Maybe one day we will come up with a way of drinking a new language. Imagine how you could mix some powder in a glass of water, drink it, and voilà: you’re now fluent in French. I don’t know what’s going on in the Silicon Valley right now, and whether we’re six months, six years or six hundred years away from creating such a powder. But until then, we have to use repetition.
Every day I learn new words. And every day I forget new words. And that’s okay. We’re only humans. SRS, memrise, duolingo, audio methods, … no matter what you’re using to learn a new language, you have to get exposed to those new words countless times before printing them in your brain.
From my point of view, the success of learning a new language comes down to three factors:
input/output + personal feedback + repetition.
There are so many ways to mix these three factors together, and thus almost an infinity of different methods to reach fluency. But no matter what, repetition is a key component of each one of these methods.