Why doesn't this create a file on the destination server? - powershell

Question

I recently did a storage migration and we had about 700 files that failed to migrate out of around 7 million (we need to purge some files, I know). I wrote the script below that is supposed to look at the corresponding file on the destination, compare the date values and if the file doesn't exist or has an older date, it's supposed to copy it over. Unfortunately, it's not copying it over. I don't get any errors but the file doesn't land on the destination. What am I doing wrong?
Also, I originally tried to grab the entire directory but it choked on the volume of files so that's why it parses each directory in turn instead.
$toplvl = "D:\Users\"
$folders = Get-ChildItem -Path $toplvl -Directory
$file = ""
$folders | ForEach-Object {
$original = $_.FullName
$dest = $_.FullName.Replace("D:","\\NewFileServer\D$")
$OutputFile = $_.FullName.Replace($toplvl,"D:\filelist-")
$FirstFind=0 #used to create a header in the output file
# Get all files under $original, filter out directories
$filelist = Get-ChildItem -Recurse $original | Where-Object { -not $_.PsIsContainer }
Write-Host $original #write directories to host to track progress
$filelist | ForEach-Object {
## Check if the file (from $original) exists with the same path in $dest
If (Test-Path ($_.FullName.Replace($original,$dest) ) ) {
## the file from $original has a match in $dest
$file = Get-Childitem -Path $_.FullName.Replace($original,$dest)
If ($_.LastWriteTime -gt $file.LastWriteTime) {
## file from $original is newer than $dest
If ( -Not ($FirstFind)) {Add-Content -Path $OutputFile -Value "Original File, Date"}
$FirstFind = 1
Add-Content -Path $OutputFile -Value $_.FullName -NoNewline
Add-Content -Path $OutputFile -Value "," -NoNewline
Add-Content -Path $OutputFile -Value $_.LastWriteTime
Copy-Item -Path $_.FullName -Destination $file.FullName
}
else {
## file from $original is same or older than $dest; can remove else statement
}
}
else {
## the file from $original is missing from $dest
If ( -Not ($FirstFind)) {Add-Content -Path $OutputFile -Value "Original File, Date"}
$FirstFind = 1
Add-Content -Path $OutputFile -Value $_.FullName -NoNewline
Add-Content -Path $OutputFile -Value "," -NoNewline
Add-Content -Path $OutputFile -Value $_.LastWriteTime
Copy-Item -Path $_.FullName -Destination $_.FullName.Replace($original,$dest)
}
}
}
Hopefully I didn't mess this up copying it over - it's my first time posting and I'm still figuring out the formatting.