Ever do a really awesome monoprint, and never be able to duplicate it? Yeah, me too.
There's a couple of ways to save you from this.
First, the easiest -- USE YOUR SCANNER! While it may not get all the shimmers if you use pearlescent or metallics, you've at least got the colours and pattern and you can always add in shimmer after you print it. This gives you MANY prints, instead of just one.
Second -- you don't have to only print one.
-- Work inside a page protector, or two sheets of acetate. When you put your paper in, use two sheets, and put them with the backs together inside the ink zone. You'll get two copies, pretty much identical.
-- A second round can then be done, and yes, it will be much lighter as most of the original ink was absorbed by the first paper, but you'll still get the same pattern and colours, and the secondary prints make great accents to work with the original.