powershell – Sharepoint Online – Recover column from lists of project sites

I have a site collection with a lot of subsites attached to projects (each subsite is a site created by a project). Those subsites has a list with its fields.

I executed a PowerShell script that excluded some columns of this list and I want to recover this columns to get the data back or perhaps a way to get this data that was lost in the execution of the script. I used to following code inside a loop:

if($fields($index).CanBeDeleted)
{
    $fields($index).DeleteObject()
    $clientContext.ExecuteQuery()
}

If there is no way to recover the field, someone has some idea how can I get the data of the excluded columns back or any other solution? Maybe a way to do some restore of data(subsite) in another URL to not overwrite the actual site?

Someone has an idea how can i solve this?

PS: I am using SharePoint Online. I have no access to the server.