Ok so go to Lowes and get some Espoma (stay away from anything that says moisture control or time released)
normally I would say soak the pot before transplant but this time is different you want to not only pay attention to how the roots look (post a pic if you can) but also gently shake any of the lose medium off (don't touch or brush the roots)
why?,,,,so others can learn
what you did was add peat to a peat based potting mix, the PH of peat is 4.5 when they use it in a soiless mix they amend it with Dolomite to offset the low PH (Dolomite raises PH and buffers over time) My guess is that enough time has gone by to offset the ability of your mix to buffer your PH properly and the peat has taken over. Indication of this is how the viens in your leaves turned a bright yellow in a manner of days plus the fact that damage is at the top (in new growth)
transplanting will give your plant a chance to recover but it will take several days
I would also get some Dolomite and add 1 tablespoon per gallon of soil to your new mix as this will help buffer what peat you still have attached to the root ball