Everybody who has been playing around with MDT faces this issue. For some changes you make you need to update your deployment point.
I got tired of clicking through the GUI to update my deployment point, so that’s why I started hacking around in Powershell to automate this process

Here’s the powershell script for updating the deployment point, it takes 2 parameters:
name of deployment point and the updatetype (Full or FilesOnly)

#'***********************************************************************
#'* File:                UpdateDeploymentPoint.ps1
#'* Creation Date:        2008/12/07
#'* Author:             Henk Hofs (Login Consultants)
#'* Purpose:            Updates MDT Deployment Point
#'* Usage:                ./UpdateDeploymentPoint.ps1 [Deployment Point Name] [UpdateType]
#'* Reference:      
#'*
#'* Revisions:              0.1   HHO     Initial Version
#'***********************************************************************
# Initialization
# Get command-line parameters for Deployment Point name and UpdateType
Param
(
 [string]$DeployName =$(throw "You must specify the name of the deployment point"),
 [string]$UpdateType = $(throw "You must specify the update type, choose between: Full and FilesOnly")
)

#Set Upd Variable (boolean) according to input from parameter
Switch ($UpdateType)
{
 "Full" {[Boolean]$Upd = 0}
 "FilesOnly" {[Boolean]$Upd = 1}   
}
#Create temp directory for log file if it does not exist
if ((Test-Path -Path C:\temp) -eq $false)
{
New-Item -ItemType directory c:\temp
}

#Load MDT Assembly
$MdtInstallDir = (gp "HKLM:\software\microsoft\deployment 4").Install_Dir
[Reflection.Assembly]::LoadFile( "$MdtInstallDir" + "Bin\Microsoft.BDD.ConfigManager.dll")
$manager = [Microsoft.BDD.ConfigManager.Manager]

#Load DeployManager class
$deployManager = $manager::DeployManager
#Load list of deployment points
$deployList = $deployManager.GetDataTable()   
# Loop through the list
foreach ($item in $deployList)
 {
 #Look for the name that was entered as a paramater
 if ($item["Name"] -eq $DeployName)
 {
 #Set $deployGUID variable and use it to update the deployment point
 $deployGUID = $item["guid"]
 Write-Host "Updating deployment point" $DeployName "with guid" $item["guid"] "using updatetype" $UpdateType
 Write-Host "Please be patient..."
 $deployPoint = $DeployManager[$deployGUID]
 $deployPoint.Generate("x86", "C:\temp\DeployUpdate.log", $Upd)
 }
 }

Well, after you updated your deployment point, you have to replace your image in WDS. So I got something for that as well… a nice oneliner in CMD

wdsutil /replace-image /image:"Lite Touch Windows PE (x86)" /ImageType:Boot /Architecture:x86 /ReplacementImage /ImageFile:"D:\Distribution\Boot\LiteTouchPE_x86.wim"

You might want to replace “D:\Distribution\Boot\LiteTouchPE_x86.wim” with the path to you imagefile

-Henk