In Level 31 you need to clear the jelly in the top squares by making either striped candies or colour bombs in the bottom half and firing them into the top..
First here's how to make a colour bomb.
Move the blue in the middle down to make a row of five blues.
This will give you a colour bomb.
The colour bomb will destroy ALL candies of the same colour that you switch it with, so here I will switch it with the green candy as there are more greens in the top half than other colours.
As you can see from the picture below a lot of the jelly is now gone from the top half.
Now I'll move the orange candy up to make a stripe underneath more jelly.
When I match the orange stripe with other orange candies it will fire upwards and destroy the jelly above it.
Here's another stripe I made as the first one fired off straight away.
To destroy the last bit of jelly I just move the orange from the side to make a group of three with the stripe and it will fire upwards where the arrow shows, destroying the jelly.
SUGAR CRUSH! With five moves left..