Gerhard's "Weiter so!" is commonly used. It's however equivalent to saying keep playing this way or keep doing what you're doing and therefore does not really fit. Same as you could say "Weiterkämpfen!", which translates to keep fighting in the sense of keep giving 100%. Both however fail to imply that the game itself now potentially reached a turning point.
The aforementioned expressions relate to a certain team and not to the game itself. Weiter so! is what a coach would say to a winning team to tell them to keep doing what they're doing. It implies a positive performance.
Weiter kämpfen! is something a coach says to a struggling team. It implies that the team is having a difficult time. It does not necessarily imply that the team is not doing well, simply that a prolonged effort is necessary to reach a satisfactory outcome.
A commentator would try not to use any of the above expressions as they imply a degree of partiality. I'm using the word try in this context because it obviously still happens frequently enough that commentators fail at being impartial.
The phrase that conveys most of the meaning you're looking for would be something along the lines of:
Es steht nun 1:2. Jetzt wird es nochmal spannend!
Es steht nun 1:2. Es bleibt spannend!
Which would translate to now it's getting interesting again! and the game remains interesting! respectively.
Both are commonly used. I have seen those in particular as well as similar constructs being used in countless football live tickers.