Steph how are you? It is a good thing to get pet insurance, even though I don't have it myself!
Regarding getting another cat, I think that is a great idea, there is no way the new one will replace Sneakers, but you have so much love to give, why not give it to another cat, that needs you! When I lost my 2 bunnies on the same day nearly 4 years ago, I went out the next day, and got 2 babies Amber and Jasmine, that helped me so much, as all my attention was on them, it didn't stop me missing Dylan and Chloe, but it helped me with the pain I was feeling at the time.. There is not one day, that I forget my bunnies, I still have their ashes in the house.. But time does heal the pain, slightly!