I have EQ so it is no problem. You need to figure out how many more blocks you will need and figure out how much fabric is used in each block. Also will need to recalculate your borders. Another untried method would be if the original pattern had 20 blocks and you want to make 30 blocks, multiply each yardage by 1.5.
Ex: 1 yard of background fabric: 1 yard x 1.5 = yard & a half of fabric