Unconfirmed txs and the Cache

Hi,

I am running a validator for testing. Some txns have somehow gotten into an unconfirmed state although they were successfully submitted.
They cannot be resubmitted because they are in the cache.

1. Why would some txns get into this state, I has 36 of them, while some were confirmed and found in their blocks?

2. is there a way to clear the tx from the cache and the unconfirmed list or be able to re-submit them?

thanks

Phill