When a contact gets deleted from Eloqua, and when they get re-created again, the contact will get a NEW contact ID. As such, form submission activity -- which is tied to the contact record through the contact ID, will NOT be associated back to the contact record.
As far as the other activities are concerned -- click-throughs, website visits, email opens, the question as to whether these activities are restored at the time of recreation depends on whether the cookie with the same GUID that the contact had prior to deletion still exists on the same machine.
Eg: Visitor browses to Eloqua using Firefox, a cookie gets dropped, and later on an association of the cookie to the contact happens -- through form submission, etc...
in order for the web activities to be restored in that scenario, that same cookie needs to be present when the contact gets recreated in Eloqua so that when the contact submits a form from that same machine, the OLD cookie that's stored in the web browser would be used to re-associate the old web activity history to the newly created history.
If the cookie is disabled or a different browser is used, the old web activities will NOT be associated to the newly created contact.
Note that there is no time limit as to how long we will keep these activities for, so time is not an issue here. You can have the activities restored to the contact above as long as the conditions above are met -- irrespective of when the re-linkage occurs.
Takeaway: As you can see from the explanation above, the chances of restoring the activities are not great -- because it's dependent on using the same browser and keeping the same cookie, and even then , you won't be able to get the form activities back.
Hope this helps