When the cooking time ends, blitz the whole thing and then add the extra chickpeas. You may need to add a bit more water if you find the consistency too thick. This often happens if you boil your soup without the lid on. But you should have it with whichever consistency you prefer, so add water accordingly. Make sure you adjust the seasoning as the water will dilute the flavour somewhat. Add some chopped parsley for flavour and colour.