If the original loan did NOT have mortgage insurance, the new loan does not need mortgage insurance, not matter how underwater you are. (MnBestRates.com)
The key is that the new loan has mortgage insurance coverage at least equal to the mortgage insurance coverage on your current mortgage. (themortgagereports.com)
You can request to have mortgage insurance removed from your loan once you believe you are at 80 % of the original loan. (mnrealestatedaily.com)