What version of Camel are you using? Its always important to write.
The splitter has an AggregationStrategy which I would assume you should be able to use to reset that flag etc.
Can you create a unit test or demo app that demonstrates this issue? Its much easier to use to track down the issue and help you.
oops... We are using camel version 188.8.131.52 in our project. Since all the split messages are getting processed in parallel, I really doubt whether it would work if the messageexchange is modified in the aggregator. It is always possible that another split message fails before the messageexchange is reset in the aggregator.
I will try to work on the test case.