Change the routine or just change the Sets and Reps??

Just wondered if it I should change my whole routine or as it says in the title just the sets and reps range? I'm doing the PUSH/PULL/LEGS routine 5x5 and have been doing it for 3months now. I had a 2week break over xmas and am thinking of switching it up in the next couple of weeks when I'll have to take another week out the gym due to work commitments. I just thought that when I come back I could shock the muscles a bit with a new routine... What would you guys recommend new routine (3days) or switch to 3x10?

Either /or really. What I do when I change set/rep is alter the exercises slightly too -so sticking with PPL but swapping back squats for front squats for a month, or even lunges. Hitting loads of flyes instead of pressing for a while etc.
 
so it's the same, only different.

As ever Bollard always giving top notch advice!! I think I'd prefer also to keep with the P/P/L routine and just switch it up a bit. What about on the PULL day, what could I change for the deadlift or is there an alternative deadlift?

Hmm, deads are a bit harder to replace - you can do SLDL's for the change period but they are much more Ham dominant, but then deads are primarily a leg exercise anyway - they're only really added to back day because the back is a secondary stimulus with them and it's too tough on the old body to squat and dead on the same day. You could do some rack pulls though from mid shin height, they're quite a good alternative.
 
I suspect you kick off back day with deads (like most do, inc. me). Why not, on your back day, kick off with rack chins (google this if you've never done them - they get a few funny looks in the gym but they're the cats knob for lat isolation), then hit some pull downs with a different grip to normal, then maybe some nautilous pullovers focussing on the bottom of the movement and finish with some rack pulls or SLDL's.
 
Then limp quietly away with you pain, smiling.

Ooohh I'm liking the look of them exercises you've suggested mate. My current PULL day consists of:
 
Deadlifts 5x5
T-bar rows 5x5
Wide grip Pull Ups 6x4 (Still not able to complete with my own bodyweight but overhand pull ups are fine??)
BB Curls 3x8-10
 
So after next week (and then my week off) it's gonna look like this:
 
Rack Chins 3x10
Pull Downs 3x10
Nautilous Pullovers 3x10 (although I'm not sure that machine is in my gym, can an alternative be doing with a dumbell lying on a flat bench or is that a whole different exercise?)
SLDL's 3x10
 
Nice little switch up or tweak the sets 'n' reps slightly??

Appreciated for the feedback mate... Given me a new sense of motivation, where I've been finding it tough the past couple of weeks hitting plateaux and my demorilising week arse chest!! lol

Ha! I know all about weak chests - my bench is mince compared with the rest of my lifts, but you gotta just keep trying new stuff.