Glad to see you here in the Community. I can share some information about reconnecting and categorizing accounts in QuickBooks Online.
You don't have to redo the categorization from Q1 if those transactions are already added in QuickBooks. In order to verify this, let's first run through your transactions under the In QuickBooks tab.
Click the Filter icon to easily look for the transactions.
Modify the date (if needed).
If the transactions are already added, there's no need for you to add them once again to avoid duplication. If not, then that's when you will have to categorize them.
As a suggestion, you can use the bank rule feature to reduce your workload and save your time categorizing the transactions:
Choose the Bank Rules tab.
Click New rule.
Enter the necessary information.
That should be enough information to answer your question.
Don't hesitate to leave a comment below if there's anything else you need or you have an additional question about banking. I'm always here to assist you. Wishing you and your business continued success.