Hey there!
This is actually a surprisingly common issue, and probably most of the videos you see online of great dancers staying up the pole forever have worked through similar problems!
First, my biggest suggestion is not to use ANY lotion prior to pole dancing. I have actually changed my own routine, instead of putting any lotion on immediately after a shower, I do it before bed. This can really help!
Second, there are so many different kinds of grip aids, and I actually have used a couple different kinds, depending on what I'm working on, what kind of pole I'm using, and the weather. Some only work a little bit, but I can still use them if I might be doing spins after a brief climb or inverted move. Others, I would never spin with! But, they are great for doing longer strings of aerial moves. My suggestion would be to test them out. Some can also be applied to the pole itself, thus saving you from immediately sweating it away.
Third, of course, are other factors. For me, I live in a very humid climate, and during the summer, it's hot! I sweat so much more, and often am quite limited in what I can train, or feel safe attempting. This can be helped with climate control, as well as lots of fans, and hand-washing (I will wash my hands a few times within an hour if it's warm out). Taking into account the finish of your pole, as well as how hard you're taxing your body, can also affect your sweating.
I have known others to get pole dancing gloves, especially for people with hyperhydrosis, which can be a big challenge for pole dancing.
For your upcoming competition, depending on the constraints of it, you might be able to do a little more of a low-flow, where you stay lower on the pole, and only climb up for moves you are very sure of, sweating or not. This can still look very impressive, and doesn't necessarily have to be super sexy if that's not your thing. Keeping things low often also requires more control and strength!
Good luck, keep trying things, and don't give up!!