Hi
Yes, definitely get the day sleeps back.
DS was a shocker (and he still has never slept through, just to put that into perspective) from around 6-7.5 months, so a similar age range.
This is a phase that will pass...

TWO things helped us -

1 - Gave up stressing about.
2 - Moved him from his cot to a mattress on the floor where we would co-sleep if he was having a bad night (much easier than getting up and down all the time). He slept much better there till he started teething around 8 months.

NCSS worked for us when he was younger, but not later on. But some of her ideas are still really helpful so I would also recommend Pantley's books.

There are several possibilities to consider - diet, separation anxiety, developmental milestones, teething... sometimes these things drag on and overlap so you never really know what is what. Leaving her to cry won't fix these problems (if that's why she's waking).

Anyway, it sucks. Sometimes you can find a problem and fix it, often you can't - just gotta ride it out and get whatever help you can along the way.