别哭了。 Don't cry.
擦擦眼泪。 Wipe your tears.
振作起来! Cheer up!
尽你最大努力! Do your best!
好好干! Do a good job!
给自己一次机会碰碰运气吧! Take a chance!
坚持下去！Keep at it!
要有信心！Keep your chin up!
再加把劲! Try harder!
别认输!/别放弃! Don't give up! 它和hang in there的意思几乎相同，只不过这种说法比较直接。
绝对不能放弃! Never give up!

只要你想做，你就一定能做得到。
You can do anything if you really want to.
You can do anything if you put your mind to it.
You can do anything if you are so minded.

那才是好样的！That's the spirit!
只要有信心，什么事都办得到。You can accomplish anything if you believe in it.

再试一遍。
Try again.
Have another try.
Do it again.
Give it another try.