I've had 3 months off time at the gym, how will this affect my performance?

I stopped going about 3 months ago as I was having exams, tests, lots of deadlines and was trying to cram it all in. After 3 months how is my weight training going to have been affected. I was doing the lot, chest shoulders, arms, back, legs etc. Is there a good way to start again or should I just go straight in attempting to do as close as possible, to what I was doing 3 months ago?