I have nothing on a replacement flag after their loss of colors (and I have two conflicting accounts for that) at Vicksburg. I am sure they got one but that might well depend on where they served again.
Sifakis' book states they were sent to the Dept. of Western Virginia. To my knowledge the troops of that department had no special battle flag and instead used a hodge-podge of flags including Second Nationals and more VA state flags (which were issued until Feb. 1865 by the way).
When they finally were attached to the ANV in March 1865, they might have received a new 7th Bunting ANV battle flag - but without a flag ID'd to this unit, we can only speculate.