Replacing Car Headliner Foam

Hello
Hope your having a Happy New Year so far.
I wanted to do my car headliner but I wasn't sure if when take out the old fabric do I have to lay out new foam or can I use the same foam?

If you are going to the trouble to replace a headliner you may as well change the foam.
They have headliners on the market now with the foam already attached to the upholstery fabric so it is only a matter of gluing the foam to the inside roof of the car.

Steve