Yes, you need to buy new sneakers!
The experts recommend you only wear your workout shoes for 6 months or 300 miles, whichever comes first. And if you wear the same shoes for more than just exercising, you will wear them out much faster. Since you have been wearing the same shoes for over a year and a half, yours are probably dead.
The cushioning and support of the shoe wears out over time. If you have a foot problem like PF, your feet are going to be more sensitive to worn out shoes. You should also consider buying two pairs of shoes and alternating them. If the shoes do not dry completely between wearing, they break down faster. If you have worn then all day, they usually need more than just overnight to really dry properly.
I have had PF for over 10 years, and the first clue I get that it's time for new shoes is that my PF flares up and my feet are stiff / painful in the mornings. I can only go 4-5 months before I need new shoes. (I only wear my workout shoes during exercise. Wearing then for everyday activities actually wears them out faster than exercising alone.)
I know it can be expensive, but think of it as a medical expense. PF is controllable, but you have to be constantly vigilant.
