There is a little more to it than just replacing one line. You have to first save the file as a PDF file, then attach the PDF file. This example just outputs the active sheet. You need more complexity if you want more sheets to go to one PDF file.
Sub reply_general()
Dim olApp As Object
Dim olMail As Object
Dim answer As String
Dim agree As String
Dim BodyCode As String
Dim str_tmppath As String
Dim PDFpath As String
str_tmppath = Environ("temp") & "\Verlofaanvraagreply.xlsm"
PDFpath = Environ("temp") & "\Verlofaanvraagreply"
ActiveWorkbook.SaveCopyAs Filename:=str_tmppath
ActiveSheet.ExportAsFixedFormat _
Type:=xlTypePDF, _
Filename:=PDFpath, _
Quality:=xlQualityStandard, _
IncludeDocProperties:=True, _
IgnorePrintAreas:=False, _
OpenAfterPublish:=False
...
.Attachments.Add PDFpath
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