I seem to have a fix for this. And even better, it seems that the reports which are still in /var/crash/*.crash can still be reported.
I started by running this for one of my recent crashes:
$ apport-cli -c /var/crash/_usr_bin_indicator-weather.1000.crash
After entering "s" to "send" the report, nothing happened. So I ran it with pdb:
$ python -m pdb /usr/bin/apport-cli -c ~/info/ubuntu/apport/_usr_bin_indicator-weather.1000.crash
(Pdb) b /usr/lib/python2.7/dist-packages/apport/ui.py:265
and discovered that the self.crashdb.accepts(self.report) test was failing.
It works to edit /etc/apport/crashdb.conf and add 'Crash' to the 'problem_types': ['Bug', 'Package', 'Crash'], or to make that change in a separate file and run
$ APPORT_CRASHDB_CONF=~/tmp/crashdb.conf apport-cli -c ~/info/ubuntu/apport/_usr_bin_indicator-weather.1000.crash
I've attached a crashdb.conf that worked for me. But I don't know if it is the right fix.