How long should it take my refrigerator to recover from adding new food to it?
Your fridge's recovery time will depend on the manufacturer and quality of appliance, how full your fridge is before adding new items to it, the density of those items, and the temperature, density, and volume of the new items.

If your fridge is normally pretty empty it's a good practice to put empty bottles in it (or better, bottles filled with water or other liquid — or, better yet, a bunch of beer :o). 

Every time you open your fridge or freezer all the cold air falls out, so the less air there is to fall out the faster it will recover and the less energy it will use.

If your fridge is filled with items with a high thermal mass (such as potatoes, not that I'm suggesting you store potatoes in the fridge), then it will have an easier job recovering. 

Never put hot foods directly into your fridge. If you make soup for another day, e.g., chill it in ice water first (obviously in a heat-proof container first) and then refrigerate it. If you put hot foods directly into the fridge it will warm up everything else in the fridge and cause the other foods to spoil faster. If you don't have ice then cold water from the tap will cool your items. If it's food that won't spoil quickly (such as a pot of beans with no meat) then letting it get to room temperature on your counter, covered, is fine. 

In the case of soup or broth, putting it into smaller containers first will let you cool it more quickly and easily. 

Also, make sure that the air vents for your fridge are not blocked. If you block them the fridge will not be able to chill itself very well.