I think it still has some oomph in it.

里面应该还有一点点茶。

The sentence works without it, but that extra pronoun gives it oomph.

这句话没有 myself 也可以，不过那另外加的代名词让句子更为有力。

Some people argue that it is important to have real oomph when making presentations.

有些人认为，在做演讲时要有真正的热情，这是很重要的。

If you put too much oomph into it, that's not a good thing, you'll go flying.

如果你太用力，这不是一件好事。你会飞起来。

I am the one with the oomph!

我就是那个有魅力的人！

It's OK to be envious of my oomph!

嫉妒我的性感是可以的！

The business owner showed real oomph in her presentation when she was pitching the idea.

这位企业主在推介这一想法时，在她的演讲里表现出了真正的热情。

Not every kind of star can explode as a supernova. The sun can't for example. It just lacks the oomph.

不是每一种恒星都会爆炸成“超新星”。太阳就不行，因为太阳的能量不够大。

Well, let's talk more about my oomph right after these examples.

好吧，让我们在这些例句之后再谈一谈我的魅力。

In a nice little hack just to give your food a little bit more of an oomph.

一个不错的使用酱料小窍门，只是为了让你的食物多一点惊喜。