Publishing of exit poll results to be allowed only on the last phase of the polling, if election is held in more than one phase. In India, generally 5% of voters do not decide till the date of polling. Exit polls, which are generally proven wrong (including this UP elections) tend to influence these 5% voter's decisions. 5% in a poll is very significant.
So, either exit polls to be allowed to publish their results only on the last phase of the polling or election commission should conduct the election in a single day. Obviosly, the latter suggestion is not feasible.