Honestly after playing 5e I would make clerics work as they do there where you get a number of spells you can prepare and you can use the spell slots to cast those spells. SO for instance you could prepare a number of cleric spells equal to your level plus some additional equal to a bonus from your wisdom score (perhaps equal to the save adjustment or something else) and those are your prepared spells for the day. You can then cast any of those prepared spells using your spell slots as normal and you choose which spell you are casting as you cast. This expends the slot but you still have the individual spell prepared so you can cast it again using a different spell slot.

If you use this then you have to consider that AD&D has more spells to do the same thing than 5e does so you may need more spells prepared than default 5e for example in 5e cure wounds is the same as cure light wounds, cure serious wounds, cure critical wounds, etc depending on what slot you cast it with.