If you love it - stick with it. If repairs are extensive (and expensive) enough to radically change the feel and playability of it, then is the time to replace it. Of my 7 guitars (all regularly used) I still tend to use my favourite - one of the cheapest, but with a beautiful sound and action. About a year ago it had its 2nd major neck job by a luthier in 25 years - in between I fiddle with repairs myself (cardboard shims under bridge and nut, etc.) I reckon in another couple of years it will need further major surgery, but until then, while people are pleased to hear it and I am happy playing it I shall continue to use it. It may even see me out. It cost £40 (pounds sterling in late 70,s - and cost me at least 4 times that in work over the years - let alone cost of strings - but outlasted 1 wife and is loved more than ever.... If it's a cheap guitar then you won't lose much, and may gain in experience and skill by doing repairs yourself - at least you'll then have some idea of when you're being ripped off. Best of luck