You can, but that's more infamy for you. Besides, whenever your vassal declares independence or war on you, you get claim on his titles automatically. If you recognise his claims and revassalise him - you are actually burning your infamy that propably caused his behavior in the first place (except if he had rebellious trait or was your rival). So, as it seem tedious, it's actually beneficial to you.
Also, you probably know this, but i mention it anyway.
* Try not to conquer too much lands in one go.
* On page 4 in your ledger you can see loyalty of your vassals and it's change. This change part is important and you get it's causes when hoverng your mouse over it.
* The dagger banner warns you if things are going bad in the vassal department.
* Feudal contract law and lowering scutage slider increases your vassal loyalty. First can cause both positive and negative events and second reduces significantly your income. (doesn't solve the problem when you have huge infamy, but can help if you need that little loyalty boost)