How do I keep a ModelMap form between forms?

I add to ModelMap

a Map

which contains the list to navigate down. I fill in the ModelAttribute when the form is initialized:

@RequestMapping(method = RequestMethod.GET)
    public String initForm(HttpServletRequest httpRequest, ModelMap model)
    {
        model.addAttribute("myList", myMap);
        return "MyForm";
    }

      

        
        
        
      

    

It works as expected, however, when the user submits the form this list is lost from the map.

@RequestMapping(method = RequestMethod.POST, value ="/dosearch")
    public String processSearch(... ModelMap model)
    {
                .....
    return new ModelAndView("MyForm",model);

      

        
        
        
      

    

This approach above doesn't work.

How can I transfer the map between form submissions?