Is there a proper way to translate "Bonne continuation" from french?

In my opinion, the difference between "Félicitations!" and "Bonne continuation!" is that the former is used to congratulate someone and to celebrate an achievment such as passing an exam for example. The latter; by contrast is usually used to express heartfelt encouragement to someone who is undertaking a project and who has reached a milestone towards its accomplishment.

I am having a hard time trying to find a proper way to find the English equivalency of "Bonne continuation!" so, any help would be highly appreciated.

An informal phrase that may be appropriate here is "Keep it up!" If I say this to you, I am telling you that you have been doing well, and so you should continue to do whatever you have been doing.

A similar phrase is "Keep up the good work!"

These phrases are commonly used alongside other phrases, as in "Well done! Keep it up!" or as in "Nicely done! Keep up the good work!"

Note that these phrases might be inappropriate to use in some circumstances. For example, I hired a contractor to work on my house, I would never tell them "Keep it up!"; I would say "I really like what you've done so far" instead. (Or maybe that's just me.)