If you had a previous VA loan foreclosed upon, you may still qualify for a new VA loan even if you have not repaid the old loan.  Currently, the foreclosure has to have occurred more than 2 years ago.

The amount you qualify for will depend on the new home purchase price and what is still owed on the old VA loan.  Each circumstance will be a little different.  A good VA lender can assist with both the process of finding what you can get, and helping you know what is needed to improve your future ability to obtain a VA loan.