Hey @Nikola_Milovic!
If you are subscribing through your application TOML, then you wouldn’t have to create a new webhook subscription. It should be automatically applied on reinstallation.
If you are subscribing manually, then you may need to resubscribe. You can query the current webhook subscription to confirm if it’s needed webhookSubscriptions - GraphQL Admin
Regarding the actual app billing subscription, since subscriptions are cancelled when a merchant uninstalls, but the charge will remain active for the current billing cycle, you will need to ensure that the merchant accepts a new charge before the end of the cycle so that the subscription can continue. There’s a great discussion here on the best way to handle this: Issue with hasActivePayment Returning true After App Reinstallation - #3 by KyleG-Shopify
Let me know if that helps.