What the OP actually asked was
Do I have to do a full PPL Skills Test again or is it just some parts ?
I repeat, it has
never been necessary to re-take any part of the [PPL] skill test in order to maintain (or regain) the currency of a PPL.
The fact that nobody seems to be able to distinguish between a PPL Skill Test and a Class Rating Proficiency Check rather makes my point about the astonishing level of ignorance out there.