You sound very frustrated. I’m not sure I can offer much help, my boys didn’t really have any difficulty with this, but I did work in a play school. The first thing I would suggest is taking a break. Don’t even go there the rest of the week. Give her, but mostly you, a break for a few days.
What other activities do you do with numbers? Do you read counting books? Does she count well? Do you give her a collection of items to count other than beans to match the number to? Do you have her trace the number with her finger? Do you have her try to draw the number? Maybe in sand, sugar or flour on a cookie sheet? What about making the numbers with playdough? Try using something other than the sandpaper numbers — like foam or magnetic numbers. Does she like crafts?
Can you make a scrapbook together where you make a number together out of some fun materials — 1 or 7 or 4 may be made with popsicle sticks that she paints, round numbers like 6, 8 or 9 could be made with pipecleaners –maybe string beads on them to help decoate them, then she would find that number of something to glue beside it — it can be something simple like foam shapes, stickers, bread tags, paper clips or even pictures of cats or clocks or butterflies that she cuts out of a magazine.
Do you have a number line on the wall or a poster? Can you just stick some construction paper numbers on the wall, give her a “fairy wand” or other stick to point to the numbers with as you call them out? Or you can lay them on the floor and call out actions to do as she moves from number to number (something like the Crainium game Hulabaloo) — Do you play games with numbers such as Bingo or hopscotch?
Just a few thoughts off the top of my head. I’m sure others will have some other great ideas.