It is just an upgrade so no not necessarily, that will be driven by how testing goes and any issues, it is not a reset and Testnet should continue on regardless of the fork.
Having to perform another fork is also a useful process to (re)test prior launch, it will definitely happen on Mainnet and last time the execution caused some issues on Testnet and was learned from. So it is a useful side benefit that it will occur again on Testnet. Not why it will happen, that is a technical change to fix the issue, but a useful benefit never the less.