The phrase "he's at it again" is correct and usable in written English.
You can use it to describe a person's actions that they often repeat, especially if they are not desired by you or by others. For example, you can say, "He's at it again, talking loudly during the movie."
Saatchi can be a bit cavalier with the works he buys and shows, and he's at it again here: Stoltmann's second piece is a tangle of tumbleweed, sprayed silver.
He already did one late-night parody of the summer's biggest hit, and now he's at it again.
Today, he's at it again in "America's Secret African Drone War Against the Islamic State," revealing wars being fought in the shadows in our name from this country's ever-changing, ever-evolving empire of bases.
He's at it again in "Rake," Fox's reprise of the Australian hourlong comedy.
But Bond's professionalism and training fortified him, and he's at it again, sans wig and age makeup, as the star of "Rites!," at (Le) Poisson Rouge, with a final performance on Feb. 3. Along with his band, led by Our Lady J, Bond performs a variety show of sorts, full of song covers and anecdotes, while teaching us how to survive the future.
He's previously turned the human face into a drum machine and a VJ tool, and now he's at it again in the music video for FaltyDL's "Straight & Arrow".
Aguero has been City's spearhead and he was at it again after only 13 minutes, showing perfect technique once more to sweep in a right-foot volley after Martin Demichelis had flicked on Samir Nasri's corner.
In last autumn's National League grand final he was at it again, tearing Widnes to shreds to secure Castleford's promotion to the Super League, and then struggling to control his emotions as he explained his reasons for joining Wakefield this season.
Labour's deputy leader referred to David Cameron's "problem with women" and claimed he was at it again.
He was at it again at Fifa's congress last week, urging delegates: "We know from our own bitter experience that this is not an easy process.
He was at it again after Monday's attack in Berlin, well before the German government had any evidence about the perpetrator or the motive behind the crime.
