Basically, you have several options for submitting form data to the server for further processing:
-You submit your form by email
-You can submit through a webservice
-You can make an HTTP submit
If you submit your form as PDF you can extract its data using "Export Data" operation of LC Forms. Are you using LC Components on the server side or have custom application? Can you specify what kind of solution do you need?
If you are using Reader then it must be Reader Extended to allow for this. The good news is that Acrobat will turn on this bit for you. Once if is Reader Extended you can use the menu item to save it locally.
Note that if you submit the data then you do not need to Reader Extend it.