If you have a conventional mortgage, you can switch to a VA loan, and enjoy the following advantages:
No monthly mortgage insurance
If you have poor credit, you may be able to get a better interest rate with a VA loan than with a conventional mortgage
No out-of-pocket closing costs
When you switch to a VA Loan, you will need to fully qualify for the loan as well as pay the VA funding fee (which you can roll into the loan). This means that the lender will treat the loan as if you were purchasing a new home with a VA Loan and they will require income, asset, appraisal and credit qualifying documentation (unlike the VA Streamline). Once you successfully refinance into your new VA Loan, you will then be eligible to refinance using the VA IRRRL (Streamline) loan if interest rates decline.