How to refreseh jsTree with new JSON data?

I have a file upload element which upon change, scans the file names and does something to get a VALID treeJSON variable (I've checked, my function works.). Now when the function detects a change the second time, obviously treeJSON is going to update and I want it to update the tree. I've tried various methods such as , refresh(), destroy() etc. But I havn't been able to contrust a new tree in the same page WITHOUT a page reload upon input.onchange.

Here is a snippet. I'vn't included all the functions. It works. Improtant part is working with the treeJSON

input.onchange = function (e) {
            \\ something
            }
            var treeJSON = someVar; 


            $('#tree').jstree({ 'core' : {
        'check_callback' : true,
        'data' : treeJSON
    } });

Any help is appreciated! Thanks