Best way to get out of a weightlifting plateau?

I have been lifting weights for a couple years now. Lately, I seem to have hit a point where I am not getting results from lifting. What is the best way to get out of a weightlifting plateau? Is it better to keep doing the same exercises and increase the amount of weight being lifted or is it better to change the exercises? Recently, I have been trying to increase the amount of weight I am lifting because I only have dumbbells and barbells, so some muscle groups are limited to a few different exercises? Is increasing the weight enough? Thanks.