If you mean guitar strings, then YES. PLEASE CHANGE THEM.
Most semi-pro guitarists, including myself, will replace strings once a month, needs permitting. Most pro guitarists will change them once a WEEK because of the amount of play they give the strings and because the tone of new strings, and the extra sustain, is useful in a recording situation.
Having your strings on for over a year is WAY too long for anyone except bassists, whose strings last much longer.
Advantages of changing guitar strings regularly -
1 - You'll get a brighter, more responsive sound.
2 - You'll get a MUCH easier feel to the guitar. Bends will be easier, moving between positions will be easier.
3 - Your guitar will sustain for longer, because it no longer has all of that gunk and stuff clogging up the windings of the strings, and the metal itself hasn't become fatigued yet, which means it will vibrate easier.
4 - You're much less likely to break a string if the set is new and has been stretched properly.
Disadvantages of string changes -
1 - If you have a floating tremolo (IE a floyd rose) then it can be a bit of a hassle at first, although once you're used to doing it its not really that bad.
2 - New strings need stretching and playing in before they'll hold tuning reliably. You can stretch the strings with your hands, or a few days of playing them regularly should break them in perfectly fine.
Your strings are WAY too old to be gigging on. I'm honestly surprised you haven't noticed the buildup of dirt and grime that MUST be on the strings and fretboard by now. Go on. Take a look at them. Take your fingernail and scrape the back or the High E string. See all the brown stuff coming off of it? Thats the dirt, sweat and grime that comes off your hands onto the string when you play. And some of that has been there over a YEAR. Doesn't that make you feel dirty and icky inside, knowing you've been touching that buildup every day for god knows how long?
Conclusion - CHANGE YO STRINGS DAWG. Your gig is in June, if you play even an hour a day, the new strings will be well and truly stretched out by the time it rolls round. I reccomend using D'addario strings.
Also, take a look at the fretboard while the strigns are being changed. Likelihood is that it will also need a clean pretty badly. Use spit, and a rag to get rid of the thick buildup. Then get some isopropyl (rubbing) alcohol and soack a tissue in it for a second. Pass that tissue over the fretboard and it will bring up all the dirt in the pores of the wood.
After that step, you'll notice you have 2 things - a really filthy bit of tissue paper, and a really dry looking fretboard. Here's where you need to buy something other than the strings - A bottle of lemon oil. You can get it from almost any guitar shop, just ask for lemon oil for a guitar, they'll find some for you. Put some on your fretboard, let it sit for 15 minutes, then wipe it away. It will nourish the wood and prevent it from cracking or splitting.
If you want to go the extra mile, I reccomend using this particular brand of lemon oil. Its cheap, easy, and its the best I've found:
Bore Oil for the Fife and Fret Doctor
Let me know if you have any questions about any of this, and DO NOT do anything you don't feel comfortable doing. Most guitar shops will do all of this
for you for a fee, some will do it for free, and ALL of them should be able to show you how to do things.