They've changed the way they follow up ladies after treatmnet for abnormalities. It used to be an annual smear smear for 10 years, but now they go more on the HPV result and often women with no HPV will be discharged back to routine 3 yearly screening. Your GP could probably confirm why you're being sent for colposcopy in a year's time, but I'd personally see it as positive, as colposcopy is a more detailed examination and better that they check you properly bearing in mind you have got CIN1. It might clear up by itself over the next year, but at least going to coposcopy is more reassuring than having to wait 3 years for a smear. I understand how scary all this though, especially if you weren't expecting to go to colpscopy.
I'm waiting my follow up after treatment for a second time. If my result is clear and I'm returned to 3 yearly screening I'll be paying for a yearly smear just so they can keep an eye on things.
I wish you all the best, take care x