It's been over a year with my ipad2 .No need to say it was as smooth as it can be? But last few months I have noticed slight Lags ESP with safari and some apps.
Is it a normal thing once the device gets old or should I reset it?
And whilst it is absolutely correct to say there is normally no need to reset / restore the iPad, you do potentially have an upcoming opportunity with the release of IOS6 tomorrow...
Whilst not required, you could choose to move to this new major version of IOS6 by doing a full restore, rather than an update. This will put a clear fresh copy of IOS6 on your device. You can then choose to either restore your last backup, or you could start afresh, depending on what suits you.
On advantage of this is that you know you are getting underway with IOS6 without any potentially unnecessary data on your device. Again, I'll be clear, it's not required, but it is a choice you have, and there is no better time to consider it than the day before a new major version of IOS is released!
I think an occasional reset, meaning holding the home button and power button together is a good idea. It certainly can't hurt. I feel it also calibrates the battery meter a little bit too. Just my take on it.