You would probably have to refinance it to get something lower, but with the prime rate going up, it may be tough to find a better rate. And refinancing will cost money. If it is a variable rate HELOC(line of credit), you may be able to refinance it into a fixed rate HEL(loan), or if you have sufficient equity in your home, you could refinance both mortgages into one loan.
What is your current rate?
I just found an article that you might find interesting:
'5 ways to tame your line of credit'