Thanks for reaching out. I hope you're enjoying the day.
Great news, yes you can upgrade to QuickBooks Online Plus. The steps to this are simple and your data will migrate over. Please note: If you used Plus before and downgraded your plan, you lost some features, by moving back up to Plus you will gain those features back. However, the data that was removed when you downgraded will not restore once you step back up but will be available to add back in manually if you wish.
Let's get you upgraded:
Go to the Settings menu and choose Account and Settings.