The bag is worked in rounds and can be made larger by increasing the base at Round 7. At each end in between the increases simply add two stitches at each end until desired size is reached. You will have to increase the length of the handles as well to accommodate the extra width.

Note that when working with Polypropylene the skeins are not always the same. I have made the same size bag multiple times with different colors and have ended with lots of leftover cord and I have run out of cord. They measure their skeins +/- 10% so try to keep an eye on that as you are nearing the end of the bag as you may have to adjust to accommodate.

When changing colors with Polypropylene the easiest way to do it is to use a lighter and to burn both ends and quickly press them together. Hold the ends together for a few seconds and they will melt together. If you tug gently they should hold. If they do not, trim the ends off and repeat the process again until they hold. It is a learning process so don’t get discouraged if it takes a few times to get it right!