how to pass a variable from a function to another function?

I am trying to setup a stripe payment option. The problem I am stuck at atm is that I want to do this as a 2-step process, where I first validate all the information filled out in the form and redirect to a new view where I take care of the payment and storing information in the database.

Problem is I cant figure out how to pass the variables in my first function to the second function.

This is the first function, for the validation process:

public function validator(Request $request)
{
    $price = Course::where('kursId', request('courseId'))->value('pris')*100;
    try {
        $data = $request->validate([
            'courseEvent' => 'required|max:11',
            'enrollmentFirstName' => 'required|max:255',
            'enrollmentLastName' => 'required|max:255',
            'enrollmentBirthDate' => 'required|max:255',
            'enrollmentAddress' => 'required|max:255',
            'enrollmentAddressNr' => 'required|max:255',
            'enrollmentEmail' => 'required|max:255',
            'enrollmentPhone' => 'required|max:255',
            'companyName' => 'required|max:255',
        ]);  
    } catch (\Exception $ex) {
        \Session::flash('flash_message_feil','Ops, det er noe som ikke er fylt riktig ut i skjemaet!!!');
        return redirect()->back();
    }
    return view('enrollmentPrivate.payment', compact('price', 'data'));
}

in my view I can use the variables just fine like this:

<form action="/charge" method="post">
    {{ csrf_field() }}
    <script
        src="https://checkout.stripe.com/checkout.js" class="stripe-button"
        data-key="{{ env('STRIPE_PUB_KEY') }}"
        data-amount="{{ $price }}"
        data-label="Betal med kort"
        data-name="Stripe Demo"
        data-image="https://stripe.com/img/documentation/checkout/marketplace.png"
        data-locale="auto"
        data-currency="nok">
    </script>
</form>

But when I try to use them in the next function for the actual charging, I get "undefined variable" error. second function:

public function charge(Request $request)
{
    dd($data);
}

This is my routes: (dont know how relevant they are tho)

Route::post('/validate', 'EnrollmentPrivateController@validator');
Route::post('/charge', 'EnrollmentPrivateController@charge');

I will be very grateful for any help I can get with this! :)