Does DTLS Change_Cipher re-transmission use same epoch as original one or the new one?
The handshake protocol retransmits its messages using the same epoch as it used in the first original transmission.

DTLS1.2 RFC6347 section 4.1 hints about it. 
However the text to reuse the  same epoch is not explicit.


  ... some care needs to be taken during the handshake to ensure that retransmitted messages use the right epoch and keying material...


For the situation where ChangeCipherSpec gets lost, it cannot be retransmitted in the new epoch. Doing so will lead the ChangeCipherSpec recipient to a situation where it does not have anyway to decrypt it because its own receive side record layer cipher state has not been updated yet with the keys of new epoch.