Apart from adding the parameters, you can also improve the code. Since you are already using jQuery.
You can replace this code:
function pictureReset(data) {
$( ".filteredImg" ).remove();
var elem = document.createElement("img");
elem.setAttribute("class", "filteredImg");
elem.setAttribute("height", "328");
elem.setAttribute("alt", "");
elem.src = 'contest/filtered_'+tempFilePath;
document.getElementById("filteredImgContainer").appendChild(elem);
}
With:
function pictureReset(data) {
var elem = $('<img class="filteredImg" alt="" style="height:328px;" src="contest/filtered_' + tempFilePath + '?t="' + $.now() + ' />');
$("#filteredImgContainer img.filteredImg").replaceWith(elem);
}
I used jQuery replaceWith for this code.