Web3 lose state when url is chaging in react

Question

I have a strange issue with my web3. Once when app is load my web3 is configured correct. I have a form on which I can submit some data to my contract and everything works great, but when I try to submit my form throw error,which says cannot access methods on my contract because is null. I start debugging and realise my web3 is actually null. Do you have any ideas how can I slove it, and how u manage to use web3 in without losing the state when url is changing. Thanks in advance