I'm really really sorry to be this way, but your betta probably isn't as happy and healthy as it needs to be. I will copy and paste a reply I typed up for another betta owner who was putting their betta in unheated and unfiltered water. (IT IS LONG BUT IT IS WORTH IT IF YOU CARE ABOUT YOUR FISH)
1.) Bettas are tropical fish. This means that they prefer temperatures around 75-82 degrees F. I doubt your glass bowl maintains that.
2.) A common misconception from first time betta owners: "I bought it in a tiny cup, so no matter what I put it in, it will be fine as long as it's not a cup!" Wrong. The goal is to have a happy, and healthy fish, right? Yes, bettas can be kept in much smaller tanks than most fish, but I doubt the vase you have it in is even a gallon. Most people will recommend for bettas a tank that is 3+ gallons. A great size is 5 gallons, and a wonderful size is 10 gallons!
Why is having smaller tanks bad for fish? It is hard to control temperature, as well as water parameters of ammonia, nitrite, and nitrates. I can't really explain those well, so please Google and learn about water parameters in tanks. But you can trust me that if you have a small tank, unless you're doing a ton of water changes (which is ALSO bad for fish) you're going to have bad levels and that is very bad for your fish.
3.) Lighting. Even indirect natural sunlight can cause bad algae blooms. This is bad.
Now, let's show you some things that would greatly improve the life of your betta.
Tank: You really should invest in a better one. Here are some examples of tanks that would be good for your fishie and aren't too expensive.
First This seems to be a good option. The only complaints I see are the lights which are easily replaceable.
Second This aquarium is VERY popular. Make sure you buy the lid that is available for it because bettas can jump.
These all come with filters. Make sure you buy the appropriate media for the filter. Now for a heater. This really should be fine for a 3-5 gallon aquarium. Basically how these work is they raise the temperature of the water about 5-10F higher than room temp. Buy a thermometer and keep and eye on it for the temps I told you and viola!
That covers the basics. You have an aquarium with filters, and a heater. That's about +10 betta happy points right there. Now for other shit
. Most water is chlorinated. Chlorine=dead fish. You need a dechlorinator. The best one out there is Seachem Prime. Follow the directions and use it in the beginning and during water changes and you're golden.
Now, there's this thing called cycling. There is a link on explaining it on the sidebar under helpful links. USE IT. Something that will speed up the cycle is Seachem Stability. I have used it with success, and many others have as well. Basically anything from Seachem is great.
You will also need to be able to check your water parameters (remember, we talked about those earlier?). Here you go. That's settled.
Now you need a substrate (gravel, sand, etc.) If you want a natural look, choose natural colors. Duh. What do I use? Because it looks good as fuck? This shit. This also helps the aquarium cycle better. You could also use plain old aquarium gravel you find at Petco. Sand, in my opinion, is easier on the eyes and easier to clean.
Now for decor. NO FAKE PLANTS NO FAKE PLANTS NO FAKE PLANTS. Get it? NO FAKE PLANTS! They will tear your bettas fins. No putting decor in a betta tank that doesn't pass the nylon test. Buy pantyhose and rub it against the decoration. If it roughs up the pantyhose, bye bye decoration. I recommend real plants. They help the water quality. A plant that you basically have to try to kill is anubias nana. You can find those at Petco/Petsmart etc. Get some Flourish Tabs to give the plant nutrients and make sure you use light bulbs that are in the 5000k-10000k range and are labeled as 'natural daylight'. Keep the lights on four about 10 hours/day. Go on over to /r/plantedtank and ask them a million questions like I did for some lernin' on lights and plant types. Seriously. Do it.
Now for cleaning. Just get a gravel vaccuum and an algae scraper and you should be fine. After your tank cycles, just do a 10-25% water change once weekly. DO NOT EVER CHANGE 100% OF THE WATER.
Food. Don't overfeed. A betta's stomach is about as big as his eye. A GREATTTT betta food is this. Give them about four pellets a day. Also supplement with blood worms and brine shrimp. You can find those at any pet store that buys fish.
You don't have to take my advice as far as brands go. But everything I listed, you really do pretty much need. Please consider these things and ask me questions if you have any. Your betta deserves to be healthy and happy.
EDIT: for more learning: http://www.bettafish.com/
http://www.aquaticcommunity.com/bettafish/
/r/bettafish