How are you converting PDF to Excel, with Adobe Acrobat or through ExportPDF/PDF Pack online service?
If using Adobe Acrobat, which version do you have? "The newer the Acrobat version is, the better your results are".
Keep in mind that converting PDF to other formats is very tricky and it only works well if the source PDF file is well formed. If you have a scanned PDF, for example, you probably won't get a good result. On the other hand, if the PDF was created from Excel through Acrobat PDFMaker and was tagged (which is the default process) you probably will get a very good result.