Decrypt connectionstring in web.cofig file

I am trying to migrate a .net application from one server to another server. Unfortunately I don't have the source code for this application but have the compiled/published version. All I intend to do is to change the connection string in the config file on the new server but the connectionstring on the config file is encrypted as below:

<connectionStrings configProtectionProvider="DataProtectionConfigurationProvider">
<EncryptedData>
  <CipherData>
    <CipherValue>encrypted cipher goes here....</CipherValue>
  </CipherData>
</EncryptedData>

I used aspnet_regiis to decrypt this file which result in an empty web.config file. Also I tried to replace this section with a different connectionstring. But upon running the application the connection string gets encrypted again. Any help on how this issue can be fixed?