Question about expanding my back patio

Im looking to expand my patio to a little over twice its current size. In total will be about 21x22. The current patio has started to crack in a few places and the slope is pretty bad. Since Id like the patio to be a bit higher can I concrete over the existing patio or will that cause problems in the future since its already cracking in a few places? The patio will eventually be covered but what is the suggested amount of slope to have? Or is there none since itll be covered?

Thanks for yalls help