turn over a new leaf
US /tɜrn ˈoʊvər ə nu lif/
UK /tɜrn ˈoʊvər ə nu lif/

1.
改过自新, 重新做人
to start to behave in a better or more responsible way
:
•
After his release from prison, he promised to turn over a new leaf.
出狱后,他承诺改过自新。
•
I'm going to turn over a new leaf and start exercising regularly.
我将改过自新,开始定期锻炼。