For the IRRRL, you'll need the Certificate of Eligibility used in your previous VA loan. For a cash-out refinance, the lender may ask for a government-issued photo ID, two years' worth of W2s, two years' worth of tax returns, copies of recent pay stubs, and your most recent bank statements.
If you are differently-abled or divorced, have ever filed for bankruptcy or have been awarded an additional Social Security card, you may be required to provide additional documentation.