This is wonderful advice- alanon is the greatest ally for troubled family members. For the alcoholic, the people of AA bring hope, love and understanding- but the families are also emerging from years of hell. Sometimes it's hard for them to see the alcoholic suddenly going "Yup, year sober! Life is great", while the husband/wife or child is still fearful going home every day, wondering what will be waiting for them.
I don't like giving advice, but did want to mention that I've known many repeat-rehabbers over the last decade. Sometimes mutiple 28 day (or three month...) stints in treatment are not the answer- sometimes sober men and women will say they paid $30,000 just to be given a big book and an AA meeting schedule.
Treatment is crucial after a long bender, or when the state of the alcoholics mind is too clouded for a simple jump back into recovery- I had to have treatment for depression when I was almost four years sober. I'm commenting based on what you said about the financial burden of another rehab (something I hear about almost weekly in meetings).
Hearing you are taking him back to a meeting is wonderful. Everyone is different, but I am not alone in the category of people who failed to heal from second, third or fourth trips to rehab- when I finally got sober, it was when I was immersed in AA and working the program. This is a long post, but I have seen every variety of recovery. If he was showing beautiful life after five months sober, there is soooo much hope there. Most people have their relapse (or more! heard it all) before they have their sobriety. Many of my friends work at or for the treatment center in our area and they would also tell you there are answers outside of treatment.
So if the money is tight, you and your friend need not fret- the answer may be only as expensive as the fuel to get him to the meeting. Just a 'maybe' to keep in mind! There are more experienced professionals who can answer that better than people on the internet.
God, I've never been able to leave short replies. Always gotta write an essay...