You can add a little lime the second time, and it probably wouldn't hurt if you add it after re-potting. I stopped adding any lime at all after the first mix. Not necessary imo. The pH is probably high enough after a year, and the water you use probably has a pH of around 7 anyway.

I also do not add lime to my 5-1-1. But I use a mostly bark based potting mix for the peat component anyway and that has already been pH adjusted.

Would the lime sink down to the rest of the potting mix when I water it or will it remain on top?

I believe you can only add it when you're making the mix and you need to wait 2 weeks for the chemical reaction to complete.

I think you can do it another way by adding Gypsum (Ca) and dosing with Epsom salts (Mg) ?

Someone smarter than me will chime in. I'm still learning myself.