May be you can use this command : sudo apt-get dist-upgrade

Have done the following:
First- "sudo apt-get upgrade deepin-software-center" and this was done without error messages but did not solve the problem. Then tried your suggestion but the process stopped at "unpackin xchat".
When running deepin-software-center in the terminal I get the following messages:

carel@carel-E145E:~$ deepin-software-center

INFO     Init ui
Traceback (most recent call last):
  File "/usr/bin/deepin-software-center", line 83, in
    start_main()
  File "/usr/bin/deepin-software-center", line 63, in start_main
    software_center.run()
  File "/usr/share/deepin-software-center/ui/software_center.py", line 1132, in run
    self.ready_show()
  File "/usr/share/deepin-software-center/ui/software_center.py", line 878, in ready_show
    self.init_ui()
  File "/usr/share/deepin-software-center/ui/software_center.py", line 833, in init_ui
    self.init_home_page()
  File "/usr/share/deepin-software-center/ui/software_center.py", line 914, in init_home_page
    bus_object = self.system_bus.get_object(DSC_SERVICE_NAME, DSC_SERVICE_PATH)
  File "/usr/lib/python2.7/dist-packages/dbus/bus.py", line 241, in get_object
    follow_name_owner_changes=follow_name_owner_changes)
  File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 248, in __init__
    self._named_service = conn.activate_name_owner(bus_name)
  File "/usr/lib/python2.7/dist-packages/dbus/bus.py", line 180, in activate_name_owner
    self.start_service_by_name(bus_name)
  File "/usr/lib/python2.7/dist-packages/dbus/bus.py", line 278, in start_service_by_name
    'su', (bus_name, flags)))
  File "/usr/lib/python2.7/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.ChildExited: Launch helper exited with unknown return code 1
carel@carel-E145E:~$

Hope this will help with finding the cause.

, please execute the above command in the terminal to install  Software Centre again.

Have tried the above but the German mirror site causes problems.
Herewith 1 of the error messages:
W: Failed to fetch ftp://ftp5.gwdg.de/pub/linux/linuxdeepi ... 4/Packages  Unable to fetch file, server said 'Failed to open file.  ' [IP: 134.76.12.5 21]
This goes on for non non-free, main, etc.
Since the Deepin-Software-Center does not work I do not know how to add the new Dutch mirror and delete the German mirror.
The latest update attempt caused the Control-Center to stop functioning.
Linux Deepin is starting to get too unstable for me.

Avoided the problem by installing Linux Mint 17. Works fine up to now.