If you go into the iOS App Store app, tap on the small circle in the upper right hand corner that shows your initials, or an image of yourself or other image ( that is your Apple account ID button ), this will bring up the account ID pop-up window.
Tap the Purchases panel
This will show ALL of the app purchases you have made and which ones are installed and NOT installed on your iPad.
Also, has a search bar, so you can search this list.
So, you can either manually search this list by scrolling until you find the app/s you wish to reinstall on this iPad OR you can use the search bar to search for the actual name of the app/s you wish to check for and re-download/re-install, if needed.
To /re-download/re-install the app, simply tap on the “cloud” symbol/icon to re download/re-instal the missing app/s back to your iOS device.
Good Luck to You!