Not sure if this works in the situation you mentioned.
To refresh an icon, or newly installed/uninstalled program's icon.
(one which has been installed/uninstalled manually)
Do this:
Open tab settings, click any program icon, then select the "pencel" to edit it.
Don't actually edit it, but select "OK" and back out of Tab settings with the "OK" button.
This will refresh the icons, but won't change anything.