If you want to keep the bad message in the original queue, then you are also blocking the messages that has arrived on the queue after the bad message.
By default Camel will retry consuming a message up til 6 times before its moved to the default dead letter queue.
If you configure the Dead Letter Channel to use maximumRedeliveries = -1 then Camel will retry forever.
When you consume a message you can check the in message header "org.apache.camel.redeliveryCount" that contains the number of times it has been redlivered.
Or "org.apache.camel.Redelivered" that contains a boolean if its redelivered or if its the first time the message is processed.