What you can do is await the pop from the next page and once that happens, you can trigger a function which re-loads your data.
Create a function called pushRoute which pushes a route on the navigator stack and use this function when you want to navigate.
As this is an asynchronous function, you can chain a .then() in the end of it. Whatever you pass to .then() will happen after the Navigator.pop() is hit on the second page.
pushRoute() async {
await Navigator.push(...);
}
...
...
//when you want to navigate to page 2, use pushRoute().
//inside the onTap of your FAB
onTap() {
pushRoute().then(() { //this .then() will be triggered when the Navigator.pop() is hit on the second page.
loadData();
}); //put all your data loading code in this function. (You can use the same loadData in the initState to load the very first time.)
}