Pull up (someone's) socks

Translation of "pull up (someone's) socks" into Russian

взяться за ум

If you want to pass the exam, you need to pull up your socks.

Если ты хочешь сдать экзамен, тебе нужно взяться за ум.

To make an effort to improve one's performance, behavior, or attitude, especially after being warned or criticized.