Best practice in adding form row - php

Question

I have a working form with a javascript 'Add Row' button, data collection and processing by PHP. While it works, the code seems fairly high-maintenance and clumsy to me (for one thing, every time I change the form I need to work the same changes into the js that adds the new row). I'm looking for suggestions to make it more sleek and simple. Currently I'm assigning each input a unique name, with hidden input that keeps track of the number of rows for me, and then I use that number to determine the amount of for loops the PHP script needs to work through to post to the database.
One thing I've considered is changing from input names to using name[], but I'm not sure if that's the right method for my needs, and how I post each row as a separate record to the database. In any case, here's the code.
HTML
<table id="table1">
<tr style="display: none"><td colspan="2">
<input type="hidden" id="samp_count" name="samp_counter" value="" />
<input type="hidden" value="sample" name="type1" /></td>
</tr>
<tr>
<td >pic caption </td>
<td>
<input type="text" name="desc1"/></td></tr>
<tr>
<td >extended description</td>
<td><textarea style="width:100%" rows="7" name="notes1"></textarea></td>
</tr>
<tr>
<td>pic file</td>
<td><input id="pic_file1" type="file" name="pic1" /></td>
</tr>
</table>
<button type="button" class="add_row" width="40px" id="samp_add_button">add row
JavaScript for the button
$(document).ready(function(){
$("#samp_count").val("1");
$("#samp_add_button").click(function(){
var iter_str=$("#samp_count").val();
var pic_id = "#pic_file" + iter_str;
if (!$(pic_id).val()){
$("#samp_error").css("visibility","visible");
}
else{
iter_str ++; // update counter
$("#samp_count").val(iter_str); //reset counter in table header to current count
var a = '<tr><td colspan="2" ><span>pic caption<input type="text" name="desc'+iter_str+'"/></span><br /></td>";
var b = '<td rowspan="3">extended description<br /><textarea style="width:100%" rows="7" name="notes'+iter_str+'"></textarea></td>';
var c = '<tr><td colspan="2" >pic file</td><td><input id="pic_file'+iter_str+'" type="file" name="pic'+iter_str+'" /></td></tr>';
$("#table1").append(a+b+c);
$("#samp_error").css("visibility","hidden");
}
});
});
PHP
<?php
if(isset($_POST['send_button'])&&$isValid==TRUE){
$user = $_POST['user'];
$count_str1 = $_POST['samp_counter'];
$count1 = intval($count_str1);
for ($i=1; $i <= $count1; $i++) {
$desc= "desc".$i;
$pic= "pic".$i;
$notes= "notes".$i;
$desc_con = $_POST[$desc];
$notes_con = $_POST[$notes];
if($_FILES[$pic]["name"]){
if( formFileUpload($pic, $user)){ //custom function to validate and upload pics-- not relevant to question at hand
$uid_path = "portfolios/".$user."/";
$file_path=$uid_path.$_FILES[$pic]["name"];
$dbh = new PDO('mysql:host=localhost;dbname=db', 'admin','pass');
$dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, 1);
$statement=$dbh->prepare("INSERT INTO portfolios (UserID, Description, FilePath, FileType, Notes) VALUES (?,?,?,?,?)");
$statement->bindParam(1,$user);
$statement->bindParam(2,$desc_con);
$statement->bindParam(3,$file_path);
$statement->bindParam(4,$_POST[type1]);
$statement->bindParam(5,$notes_con);
$statement->execute();
}
else{
$fileErrorDis="inline";
$isValid=FALSE;
} }}
?>
Link to working website -- self-explanatory but text in Hebrew (in some of the forms, the js has not been updated and the new row does not resemble the original one)