SRD:
Psychic Reformation
Telepathy [Mind-Affecting]
Level: Psion/wilder 4
Display: Auditory, mental, and visual
Manifesting Time: 10 minutes
Range: Close (25 ft. + 5 ft./2 levels)
Target: One creature
Duration: Instantaneous
Saving Throw: None
Power Resistance: No
Power Points: 7, XP; see text
When this power is manifested, the subject can choose to spend its most recently gained skill points differently (picking new skills and abandoning old ones if it chooses) and to choose a different feat from the one it selected when advancing from its previous level to its current level.
The subject can also choose to forget powers it acquired when advancing to its current level, replacing them with new ones.
The subject can undo decisions of these sorts that were made at lower levels, if both the subject and the manifester agree to pay the necessary XP before this power is manifested (see below). The subject must abide by the standard rules for selecting skills and feats, and so it cannot take feats for which it doesn’t qualify or take crossclass skills as class skills.
XP Cost: This power costs 50 XP to manifest to reformat choices made when the character reached her current level. For each additional previous level into which the revision reaches, the power costs an additional 50 XP. The manifester and subject split all XP costs evenly.
Emphasis mine.
You must follow the normal rules for picking what you can pick. Taking this, and the rest of the power, to mean what it would imply in a general sense then whenever you go back X levels you work up one level at a time but all choices must be those you could have made for that level.
This means that if you are level 20 and use it for all 20 levels of your character then you go back to level one, pick what you could pick, then move on to level two. continuing all the way up until you are done. You cannot pick things that you could not have picked at that point, you cannot make illegal choices (so if you have prc Y at level Z then you have to have the prereqs for it before you move on into it, otherwise you are making an illegal choice.)
Going by that make the power pretty much fine as is. Taking it outside of those bounds is not a good idea (in a similar fashion to not allowing fireball to do more than 10d6 damage).