Children aren't really like adults. They forget their old friends very quickly, as they move on into their new experiences and start to build new social circles.
I work in a school with a high turnover due to service children and find that, generally, incoming children bond quickly with 'similar' children in the class, whoever you've given them as a 'buddy'. (I put 'similar' in quote marks, because the 'similarity' could be horseriding, Barbie, level of conversation, flute playing - all manner of things). Most seem to have a 6th sense that helps them choose friends appropriately within hours of arrival.
As regards old friends - it's usually mummy reminding them about them, that sparks a vague memory! (And that is very important - I'm not saying you shouldn't do it by any means!)
We find that children who get upset are those who do not like change in routine. They are shoved into a new environment that is very strange to them. These are the children who miss their old school and miss their old friends. They are very few and far between. I've had 9 new year 2s this year and none of them have cried at all. (Four of these started by themselves part way through the year.)
As your child is starting in September, with all the rest of the children, after a long holiday, there should be no problem whatsoever.
And well done to your DD Elokitty - it's sometimes not easy to move this term!