The 助動詞（じょどうし） (auxiliary verbs) よう and う in standard Japanese will be altered slightly in 関西弁（かんさいべん）. In each case, this will simply result in removal of the う. This means that the meaning of ‘let’s’ or ‘I shall’ will be conveyed by either よ by itself (in the case of る - Verbs, する, and くる), or the form of う - Verbs that would usually interact with う (the terminal kana changed to create an お sound).
I'm starving. Let's eat takoyaki.
Let's go to Universal Studios Japan the day after tomorrow.
Our place is getting messy, so let's clean our apartment tomorrow.
Let's come here to eat next week.
The verb form that よう and う interacts with is actually called 未然形（みぜんけい） (indeterminate form), and is used for conveying things that have not happened yet. う - Verbs are slightly different to other verbs in this regard, as they have two indeterminate forms. One of them is the form that interacts with う (the お sound kana), and one of them is the form that interacts with ない (the あ sound kana).
私（わたし）は泳（およ）げないので海（うみ）には行（い）かない。 (Indeterminate form)
I can't swim so I don't go to the beach.
明日（あした）みんなで海（うみ）に行（い）こう！ (Also indeterminate form)
Let's go to the beach tomorrow, with everyone!