Your LTV rate can change based on the amount outstanding reducing and your house value changing up or down. This can be a huge factor in securing a new Mortgage rate.
If you are locked into a fixed rate with your current lender and you opt out of it early, there may be a breakage cost to pay. This can vary from lender to lender.
The balance outstanding on your current mortgage will be a determining factor when looking to switch mortgages. Both minimum and maximum mortgage terms can apply if you are switching.