You might have a look at the Resource room
section of the forum - the thread on dictionaries may discuss this topic.
The only two on-line dictionaries I know of that are anything near comprehensive are shabdkosh.com
and the Platt's dictionary of Urdu and Hindi
. Shabdkosh.com, though, won't help you that much with filmi Hindi-Urdu - its focus is more on shuddh Hindi. Platt's, on the other hand, will have most of the words that you are likely to encounter in filmi songs. Its a little confusing to use at first but once you get the hang of it you will see how comprehensive it is. One caveat: Urdu words are not in Devanagari in Platt's, so you may do better searching in transliterations than in Devanagari for some filmi lyrics,
When I do translations I tend to work in paper, rather than on-line - and I have almost never managed to stump my trusty Oxford Hindi-English dictionary. The only words I couldn't find in there were a couple of words from a song that was intentionally written in very chaste Urdu.
Welcome to the forum, and I hope you will join our discussions as well.