Powershell Update an already active form - forms

Question

So I'm trying to insert red dots into some kind of map, which I do with creating new pictureboxes after reading their coordinates out of an txt-file.
My goal now is to remove or create new boxes, while the form.ShowDialog() was already used.
I found a way of closing the whole form and running everything again, which kind of works but is very ugly in my opinion. Was wondering if there is another way of checking if new coordinates have been added to the txt-file or removed and if that is the case, creating or removing the corresponding boxes.
(I tried .Refresh but that seems to do nothing at all)
function MakeForm {
[void][reflection.assembly]::LoadWithPartialName("System.Windows.Forms")
[System.Windows.Forms.Application]::EnableVisualStyles();
$form = new-object Windows.Forms.Form
$form.Text = "Image Viewer"
$form.Width = 270;
$form.Height = 270;
$path = (Get-Item "Insert Path here")
$path2 = (Get-Item "Insert Path here")
$img = [System.Drawing.Image]::Fromfile($path);
$img2 = [System.Drawing.Image]::FromFile($path2);
$test = Get-Content -Path "Insert Path here"
$test
$pictureBoxes = New-Object 'System.Collections.Generic.List[Windows.Forms.PictureBox]'
$i=1
Foreach ($Line in $test){
if ($Line -like "*in 2*"){
$i++
$Split1= $Line.Split(" ")
$x=$Split1[5]
$y=$Split1[6]
$pictureBox = New-Object Windows.Forms.PictureBox
$pictureBox.Width = $img.Size.Width;
$pictureBox.Height = $img.Size.Height;
$pictureBox.Location = New-object System.Drawing.Size($x,$y)
$pictureBox.Image = $img;
$form.Controls.Add($pictureBox)
$pictureBoxes.Add($pictureBox)
Write-Host $pictureBoxes[$i]
$form.Add_Shown( { $form.Activate() } )
}
}
$pictureBox20 = New-Object Windows.Forms.PictureBox
$pictureBox20.Width = $img2.Size.Width;
$pictureBox20.Height = $img2.Size.Height;
$pictureBox20.Image = $img2;
$form.Controls.Add($pictureBox20)
$button1 = New-Object System.Windows.Forms.Button
$button1.Width=25
$button1.Height=223
$button1.Location = New-Object System.Drawing.Point(223,0)
$form.Controls.Add($button1)
$button1.Add_Click({
#Button for removing a box for testing purposes
$form.Controls.Remove($pictureBoxes[3])
})
$button2 = New-Object System.Windows.Forms.Button
$button2.Width=25
$button2.Height=223
$button2.Location = New-Object System.Drawing.Point(260,0)
$form.Controls.Add($button2)
$button2.Add_Click({
#This Button should refresh the whole form, if possible without doing everything again
$form.Close()
$form.Dispose()
MakeForm
})
$form.Add_Shown( { $form.Activate() } )
$form.ShowDialog()
}
MakeForm