flutter drawer removes items when closed - flutter

Question

I have a drawer where the user can add items to it which are links to a different page. It works, but if I add an item and then close the drawer, when I open the drawer again that item is gone (other than the default one I have in a list). I have the code below
class SkillDrawer extends StatefulWidget {
#override
State<SkillDrawer> createState() => SkillDrawerState();
}
class SkillDrawerState extends State<SkillDrawer> {
List<Skill> _skills = [
Skill(title: "Test Title 1", pointCap: 500, id: DateTime.now().toString())
];
void _addNewSkill(String sklTitle, double sklPoints) {
final newSkill = Skill(
title: sklTitle,
pointCap: sklPoints,
id: DateTime.now().toString(),
);
setState(() {
_skills.add(newSkill);
});
}
void _startAddNewSkill(BuildContext ctx) {
showModalBottomSheet(
context: ctx,
builder: (bCtx) {
return NewSkill(_addNewSkill);
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Drawer(
child: ListView(
padding: EdgeInsets.zero,
children: [
const DrawerHeader(
decoration: BoxDecoration(
color: Colors.blue,
),
child: Text('Subjects'),
),
// ## the container listing added items to drawer
Container(
height: double.maxFinite,
child: ListView.builder(
itemBuilder: (ctx, index) {
return ListTile(
title: Text(_skills[index].title),
onTap: () =>
Navigator.of(ctx).pushNamed('/skills', arguments: {
'id': _skills[index].id,
'title': _skills[index].title,
}));
},
itemCount: _skills.length,
))
],
),
),
floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
floatingActionButton: FloatingActionButton(
child: Icon(Icons.add),
onPressed: (() => _startAddNewSkill(context)),
),
);
}
}
I want to make it so that the items are not cleared when the drawer is closed, until the app is closed of course.