If you're changing to another visa, your best bet is to just carry on with the OVHC cover that you already have. For example, if you are on a temporary graduate visa (485) and are switching over to a temporary skill shortage visa (482).
If you've got your PR, then you are not required to keep your OVHC – but make sure you don't cancel before you get it. Once your PR has been approved, you will be eligible for private health insurance like most Australians.