Cut into crochet project

I was trying to add length to a sweater. I started at the bottom to work down and of course the stitches weren't as I had been working because that part had been the first stitches chained. I then took scissors and cut through thinking I could pull small threads out and follow old stitches. Now I have a real mess. Do I have to forfeit the whole side of the sweater now and start over or is my project salvagable? From now on when I want something longer than the pattern should I start crocheting from the bottom up and get it at the "extra" length I want it and then start following the pattern? I'm not very good at this as you can tell. Any help will be appreciated. Email is Thank you.