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

1.
à la réflexion, en y repensant
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.
Je vais prendre le poulet, non, à la réflexion, je vais prendre le poisson.
•
Let's go to the park. Actually, on second thought, it might rain.
Allons au parc. En fait, à la réflexion, il pourrait pleuvoir.