If you're at all worried, I'd suggest getting 0.5ml liquid paraffin in her. I personally would use 1ml, but opinions differ on how "safe" that is (never had a problem myself at that level).
Follow this up a few hours later with probiotic such as Avipro or Bio Lapis to help repopulate any gut bacteria that might have been scoured out by the laxative.
The great thing with liquid paraffin is not only does it help soften anything in teh digestive tract to aid passing it, but it also helps break down various plastics, so if the ribbon was synthetic fibre (almost certain) then the liquid paraffin not only aids moving it, but helps throug reducing the size of the peice that would have to be passed.
Edit - Also agree with above on monitoring what comes out. It's roughly 6 hours between food in and poo out in a healthy piggie, so you want to be seeing healthy poo at least every 6 hours. Also need to be seeing things going in the front! If she doesn't pass a vast amount and starts to show signs of gas, then Infacol (again, I give 1ml, but others will say around half that) will help a little with that, but a trip to the vet will be vital if her guts slow down and gas starts to build up.
