I agree with Tom's explanation. The expression "take it up a notch" also means 'to try harder / make more effort / to make something more exciting, intense, or interesting'. The expression is sometimes written as "Kick it up a notch". It has the same meaning as "take it up a notch". For example: The sports team was losing the game, so the leader of the team told the other players to "take/kick it up a notch".

Hi Hoon, it means the same as the first part of the sentence says - "to go to the next level". Imagine a "speed dial" that has little marks that represent the speed. The faster and faster you go, the more little marks the dial points to. These little marks are called "notches". Does that make sense? Tom