Anyway, you know that how much I like it.

that 就是 how much I like it
you know that 或者 you know how much I like it.

因为后面是一个短语，没有主谓结构，所以不能用宾语从句，自然要把that去掉

how much I like it为宾语从句，that做连词引导宾语从句，通常省略掉，加上也不错。