ASP.NET - how to create interactive PDF form in asp.net (add/update enabled)

I wants to create a PDF form which will get displayed on web, and have textbox, label and html controls
which enables end user to update data

You'd have to use ActiveX in the browser for this.  You could create an html form that looks like your PDF document and then generate the PDF from the form values.  Aspose.com has a nice PDF product.