You can easily replace one object by another while keeping its position, its timing and even its animation settings.
To do that, first make sure you have the new object available in your Library. If the new object is, for example, a picture, make sure you've uploaded it to your Personal Library.
Select the object you want to replace. You will see its Object Settings in the top right area of the Editor. Click the "Swap Object" option. Next, drag your new object from the library and drop it in the dashed object placeholder. That's all! Now your new object has replaced the original one.
The timing and animations of the original object will also apply to the new object, except for special animations that are object-specific.