How long do I need to keep tying my plants down?

Hi I'm at weed 3 almost 4 veg. I've lst and topped about 1 week ago.
my question is should I tie the plants down again? They are about 1.5ft.

That's all up to you. It's strain specific or how much room/ time you have. Just don't flip until 2 weeks after last tie down.

It all depends. LST can go on for months if you have the room.