问一个问题，JS省市联动菜单提交服务器程序返回怎么保存提交前的省和市

如题：就是我选安徽省，安庆市提交后返回又变成初始值了。代码如下：
<html>
<head>
<title>全国省市</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<style>
body,select
{
font-size:9pt;
font-family:Verdana;
}
a
{
color:red;
text-decoration:none;
}
a:hover{
text-decoration:underline;
}
</style>
<SCRIPT LANGUAGE="JavaScript">
<!--
function Dsy()
{
this.Items = {};
}
Dsy.prototype.add = function(id,iArray)
{
this.Items[id] = iArray;
}
Dsy.prototype.Exists = function(id)
{
if(typeof(this.Items[id]) == "undefined") return false;
return true;
}
 
function change(v){
var str="0";
for(i=0;i<v;i++){ str+=("_"+(document.getElementById(s[i]).selectedIndex-1));};
var ss=document.getElementById(s[v]);
with(ss){
  length = 0;
  options[0]=new Option(opt0[v],opt0[v]);
  if(v && document.getElementById(s[v-1]).selectedIndex>0 || !v)
  {
   if(dsy.Exists(str)){
    ar = dsy.Items[str];
    for(i=0;i<ar.length;i++)options[length]=new Option(ar[i],ar[i]);
    if(v)options[1].selected = true;
   }
  }
  if(++v<s.length){change(v);}
}
}
 
var dsy = new Dsy();
 
dsy.add("0",["安徽","北京","福建","甘肃","广东","广西","贵州","海南","河北","河南","黑龙江","湖北","湖南","吉林","江苏","江西","辽宁","内蒙古","宁夏","青海","山东","山西","陕西","上海","四川","天津","西藏","新疆","云南","浙江","重庆"]);
 
dsy.add("0_0",["安庆","蚌埠","巢湖","池州","滁州","阜阳","合肥","淮北","淮南","黄山","六安","马鞍山","宿州","铜陵","芜湖","宣城","亳州"]);dsy.add("0_1",["北京"]); 
dsy.add("0_2",["福州","龙岩","南平","宁德","莆田","泉州","三明","厦门","漳州"]); 
dsy.add("0_3",["白银","定西","甘南藏族自治州","嘉峪关","金昌","酒泉","兰州","临夏回族自治州","陇南","平凉","庆阳","天水","武威","张掖"]); 
dsy.add("0_4",["潮州","东莞","佛山","广州","河源","惠州","江门","揭阳","茂名","梅州","清远","汕头","汕尾","韶关","深圳","阳江","云浮","湛江","肇庆","中山","珠海"]); 
dsy.add("0_5",["百色","北海","崇左","防城港","桂林","贵港","河池","贺州","来宾","柳州","南宁","钦州","梧州","玉林"]);dsy.add("0_6",["安顺","毕节","贵阳","六盘水","黔东南苗族侗族自治州","黔南布依族苗族自治州","黔西南布依族苗族自治州","铜仁","遵义"]); 
dsy.add("0_7",["白沙黎族自治县","保亭黎族苗族自治县","昌江黎族自治县","澄迈县","定安县","东方","海口","乐东黎族自治县","临高县","陵水黎族自治县","琼海","琼中黎族苗族自治县","三亚","屯昌县","万宁","文昌","五指山","儋州"]); 
dsy.add("0_8",["保定","沧州","承德","邯郸","衡水","廊坊","秦皇岛","石家庄","唐山","邢台","张家口"]); 
 
dsy.add("0_9",["安阳","鹤壁","济源","焦作","开封","洛阳","南阳","平顶山","三门峡","商丘","新乡","信阳","许昌","郑州","周口","驻马店","漯河","濮阳"]); 
 
dsy.add("0_10",["大庆","大兴安岭","哈尔滨","鹤岗","黑河","鸡西","佳木斯","牡丹江","七台河","齐齐哈尔","双鸭山","绥化","伊春"]); 
dsy.add("0_11",["鄂州","恩施土家族苗族自治州","黄冈","黄石","荆门","荆州","潜江","神农架林区","十堰","随州","天门","武汉","仙桃","咸宁","襄樊","孝感","宜昌"]);dsy.add("0_12",["常德","长沙","郴州","衡阳","怀化","娄底","邵阳","湘潭","湘西土家族苗族自治州","益阳","永州","岳阳","张家界","株洲"]);//-->
</SCRIPT>
<SCRIPT LANGUAGE = JavaScript> 
var s=["s1","s2"];
var opt0 = ["渠道","全部"];
function setup()
{
for(i=0;i<s.length-1;i++)
  document.getElementById(s[i]).onchange=new Function("change("+(i+1)+")");
change(0);
}
//-->
</SCRIPT>
</head>
<body bgcolor="#E0E0E0" onload="setup()">
多级关联菜单：
<form name="frm" action='del.php' method='post'>
<select id="s1" name="s"><option>省</option></select>
<select id="s2" name="x"><option>市</option></select>
</form></body>
</html>