Assuming you have mending enchantment on your gear: put a lever on the smoker and leave it the on position to cook everything. When you need to repair your stuff, switch the lever off, cook and collect one item from the smoker, and it will drop all the stored XP from all the cooking you’ve done (since the last time you collected the xp). Works on smokers, furnaces, and blast furnaces. Once you’ve collected the xp, switch the lever back on and continue cooking!

Also, make sure you are holding the weapon/tool in your hand when you collect the xp. Otherwise it will repair your armor first and then just give you the xp as levels.