Well, I did not found any reconnect script for the FrritzBox 7390 which does NOT utilize uPnP. So I wrote one by myself.
For everyone out there who does not understand why I did this: It is a fact that uPnP could be a security risk. If you use uPnP to configre yor router/nat/firewall it usually is a security risk.
This script is a Powershell script. (Well, Powershell is a command prompt written by Microsoft. On Windows 7 it is installed by default.)
Installation instructions coud be found in the script.
The file extension for powershell scripts is "ps1". So you may put the following script into a file called "reconnect.ps1".