on second thought
US /ɑːn ˈsek.ənd θɑːt/
UK /ɑːn ˈsek.ənd θɑːt/

1.
考え直したら, 改めて考えると
used to say that you have changed your mind or that you have a new idea that is better than your previous one
:
•
I'll have the chicken, no, on second thought, I'll have the fish.
チキンにします、いや、考え直したら、魚にします。
•
Let's go to the park. Actually, on second thought, it might rain.
公園に行こう。いや、考え直したら、雨が降るかもしれない。