If you are having a problem with your heal ripping from the boot you should think about sending them back to the manufacturer (especially if it’s within a year of buying them). If it’s not covered under the warranty they can usually fix it anyway for under a hundred bucks. But here is an even cheaper way of fixing it!
You can buy fiberglass kits at the hardware store. Make sure your skates have had a couple days to dry completely. Also, don’t try this unless you have another couple days for the fiberglass to dry afterwards (otherwise it will definitely come apart!).
Use a large vise to keep the boot and heel tightly together. Mix the resin and apply it with a brush to the back of the boot, heel and fiberglass material. Apply the fiberglass to the heel and boot in layers. Make sure that you don’t apply it where any stress from the boot would place any stress on it. Make enough layers for it to be really strong when it dries…and voila!