Hi Kristine
Staying with the bank you are with can sometimes be an advantage because if you refinance with them to a higher amount, they will often not charge break fees etc.
You will possibly still have to pay a new application fee, but some of the legal fees will be a lot lower because they already have security on your property.
I have just refinanced with my bank to get access to equity in one of my IP’s, but have then gone to another bank for a loan for another IP, the reason I went to another bank was that for this IP I am borrowing at 90% and therefore I will only pay Mortgage Insurance on the one property.