Ahem. To advance a creature's CR you potentially need to take these steps:
1. Check its type to determine how many hit dice it should gain for each "level-up"
2. Advance ability scores based on hit dice
3. Advance size and resulting strength/dex/con modifiers, natural AC, and attack/defense modifiers
4. Advance base damage die of all the creature's natural attacks and calculate attack and damage values for primary vs. secondary natural attacks
5. Add feats
6. Recalculate BAB, AC, touch AC, flat-footed AC, grapple bonus, HP, fortitude, reflex, will, SR, DR, caster level, save DC of spells and spell-like abilities, and all skill bonuses based on hit dice, creature type, size, ability score values, armor worn, and any feats.
In 4e, to advance a creature's level this is reduced to the following:
1. Pick an arbitrary level you wish to advance the creature to.
2. Check the NPC advancement table for the new HP, AC-attack, NAD-attack, and fort/ref/will modifiers.
3. Advance damage of the creature's attacks, also based on the table.
4. Optionally, advance the size. All this changes is melee reach and area.
5. Optionally, pick new arbitrary values for initiative and any ability scores or skill bonuses.
6. Optionally, if you're advancing a creature a full tier, you might want to give it another arbitrary ability for each tier (paragon, epic). This isn't any more difficult than picking a feat or two.
Sorry but I'll take
[URL=http://www.enworld.org/forum/usertag.php?do=list&action=hash&hash=2]#2 [/URL] any day.