I have taken the binding off a quilt to enlarge the quilt, because of new mattress and box springs. I then added the new border, batting, and backing and quilted it on my domestic machine. Reused the binding, adding more length as needed. Not a fun job, but doable.
I also added additional border to a quilt that I had just completed on my long arm, because I decided I liked it more than I thought I would and wanted it on my bed, (requiring more border), versus the guest bed. That was trickier, because of the quilting and needing to load it on the long arm, quilt the side borders...add the top and bottom borders, then load it again on the long arm, quilt the top and bottom borders.
I'll try not to do that again, but it is doable.