For a temporary solution this will help, but you need to find a better location to continue with this exercise. You can add 1 rep every workout you complete the required reps from previous. So if you completed the 5 reps this past workout, then add a rep next scheduled workout for a total of 6, then you could keep this up to maybe around when you can complete 8-10 reps, but then you really should have another solution worked out so you can add weight, because while volume will drive strength (which is what you are doing by adding reps), the more optimal for strength increase is to add weight which causes even greater adaptation strength-wise. I think there is a program called All Pros that does this protocol of adding reps (thus volume) to a given exercise till a threshold is reached, then weight is added and you start back at lower rep range and work back up, rinse and repeat. This program though does not have a higher strength focus like StrongLifts in my opinion and while of course you will get stronger (it will be slower), there is a body-building aspect to it due to the higher volume which takes away the focus on optimally building strength; especially in a beginner.

You'll get better results in the long term if you stick to the program, which means you need to find a way to add weight to the bar. Do you really need that ceiling? ;-)