Notes for extending the pattern repeat:
Add 2 means: each subsequent time that you work Chart A, you will work a further 2 stitches in garter st before starting the lace pattern and one extra lace repeat
In row 13: add 2 st in the k10 (as in you have 2 more sts to knit, because of the increasing in the begin of the row). Next repeat will read as:
Row 13: (k1, yo) 3 times, k10+2=k12, yo, s2kp, yo, (k5, yo, s2kp, yo) to last 4 sts, k2, (yo, k1) twice
Row 14: add 1 repeat between brackets. Next repeat will read as:
Row 14: k5, yo, k2tog, k1, ssk, yo, (k3, yo, k2tog, k1, ssk, yo) 3 times, k to end. Next repeat will be 4 times then 5 times and so on.
In row 15: add 2 st in the k13. Next repeat will read as:
Row 15: (k1, yo) 3 times, k13+2=k15, yo, s2kp, yo, (k5, yo, s2kp, yo) to last 6 sts, k4, (yo, k1) twice
Also the blocking diagram isn't correct, it's showing a symmetrical shawl, please look at the picture of the minishawl to see the correct shape.
So back to the design itself, it's worked top-down in garter stitch, the lace pattern is made by working increases and decreases in RS and WS rows. The shaping of the shawl is a-symmetrical and as just the way I like it, you can customize the shawl to use all availabe yardage. It also has an option to make a buttonhole to fasten the shawl so it won't slip of your shoulders. So here are the pics from The Knitter.