Why has my old Shopify app stopped working due to expired API keys?

[Ninad27]

We have shopify app developed long back. our client has mentioned that it has stopped working, it looks like the 

SHOPIFY_API_KEY and SHOPIFY_API_SECRET is expired it is giving unauthorised error.

I have also observed that we have some deprecated packages in use.

list of deprecated packages that we are using -

@Shopify/app-bridge-utils

@Shopify/koa-shopify-auth

If I create new app from partner and start using old code with it does work on local, It may take time for us to adopt and migrate to new code base, till then I just want to know if we can do anything to get old app working, so our clients will be unblocked.