Assuming that (a) you have saved your Passwords and other account credentials in your iPads Saved Passwords (i.e., your Keychain) - and (b) enabled iCloud Keychain - all your Passwords will be safely stored in iCloud and will survive a reset of your iPad:
Settings > [Your Name / AppleID] > iCloud > [Apps Using iCloud] Passwords & Keychain > Sync This iPad - set to ON
Your iPad can be fully reset from iPad settings:
Settings > General > Transfer or Reset iPad > Erase All Content and Settings
After reset, you can setup your iPad from the initial "hello" page with your AppleID. Any data stored in iCloud - including your saved Passwords - will be copied/synchronised back to your iPad.