Can I continue to deduct interest from my new home primary mortgage for that portion remaining that was used to purchase the rental property?

I used a home equity line of credit as down payment on a rental property and have been deducting interest. 

If I sell my primary residence then the loc is paid off.  However, if I am purchasing a new home, the portion that I was paying is now rolled into a new mortgage.  

I want to keep deducting interest on the amount remaining that was used to purchase the rental. 

Can I pro-rate a portion of my new home mortgage insurance that now includes the paid off loc after the sale?