The onus of changing the account type from resident to NRI vests entirely on the client if he is a non-resident of India for an uncertain period.
Either way, a resident account cannot be converted to an NRE account, it can only be converted to an NRO account. Since you have an NRE account, you will have to close your resident account, open an NRE account and continue investments there.
You can transfer the shares and MF units in your resident demat account to your wife’s resident demat account using a DIS slip before you close your resident account.
More reading material in the posts below:
https://zerodha.com/z-connect/zerodha/open-an-account/nri-trading-on-indian-stock-exchanges