validating dynamic text box content in PHP - php

Question

I have this and works fine. But can someone tell me is there a SMARTER way to validate this?
In the validation here, you may find that the echo "<form....... is replicated thrice to make sure that the form content is also visible along side the validation message when the form is submitted. Im sure there is a more refined method of validating text box content without form being replicated multiple times.
Also appreciate if some one can suggest me a method to retain the text box value after the form is being submitted. Usually when the form is submitted the value you enter disappears.
Thanks
<?php
include ("../connection/index.php");
?>
<form method='post' action=''>
<input type="submit" name="sendone" id="sendone" value="OneClick">
</form>
<?php
if(isset($_POST['sendone']))
{
echo "Hello";
echo "<form method='post' action=''><input type='text' name='txt1' id='txt1'><input type='submit' name='sendtwo' id='sendtwo' value='TwoClick'></form>";
}
if(isset($_POST['sendtwo']))
{if($_POST['txt1']=='')
{
echo "Hello";
echo "<form method='post' action=''><input type='text' name='txt1' id='txt1'><input type='submit' name='sendtwo' id='sendtwo' value='TwoClick'></form>";
echo "Empty";}
else
{
echo "Hello";
echo "<form method='post' action=''><input type='text' name='txt1' id='txt1'><input type='submit' name='sendtwo' id='sendtwo' value='TwoClick'></form>";
echo "Hit success!";
}}
?>
EDIT
Concept
<hard coded submit1 button>
<dynamically create a text box with a submit2 button>
<when submit2 is activated is should validate the text box content>
When the validation happens both the vaidated message and the text box should be visible

Answer 1

did you mean something like this?
<?php
if(isset($_POST['sendtwo']))
{
echo "Hello";
}
?>
<form method='post' action=''>
<?php
if (!isset($_POST['sendone'])) {
?>
<input type="submit" name="sendone" id="sendone" value="OneClick">
<?
} else {
?>
<input type="hidden" name="sendone" id="sendone" value="OneClick">
<input type='text' name='txt1' id='txt1'<?=isset($_POST['txt1']) && trim($_POST['txt1']) !== '' ? ' value="'.trim($_POST['txt1']).'"' : ''?>>
<input type='submit' name='sendtwo' id='sendtwo' value='TwoClick'>
<?
}
?>
</form>
<?php
if (isset($_POST['sendtwo'])) {
if (trim($_POST['txt1']) == '') {
echo 'Empty';
} else {
echo 'Hit success!';
}
}