Resetting a form via settings variable

In my form, I got a class named Cform which is subclassed to ConstanceForm Cform(ConstanceForm)

In my views.py

class ResetCView(FormView):
    template_name = 'c.htm.jinja'
    form_class = Cform
    model = CModel

    def form_valid(self.form):
        form.cleaned['C_CODE'] = settings.C_CODE
        form.save()
        retu HttpResponseRedirect(reverse('cview))

In my template:

<form method="post" action="{{url('c-reset')}}" name="form">
          <button>Reset</button>
</form>
<form method="post" action="{{url('c-view')}}" name="form">
          {{ form.as_p}}
</form>

My problem is it is not updating. Form is always invalid. I just want to reset my form or its database value to a specific data.